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Ammeter/Main Voltage Fluctuating #1144379
12/26/11 05:11 PM
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I started a new thread focusing on just my ammeter issue.
The below car has an issue with the ammeter bouncing around from just left of the center mark (1/4" or so) to the positive side of the ammeter about 3/4 up on the guage.
At idle, the ammeter is bouncing back and fourth fairly fast and when I bring the idle rpms up to around 1400rpms or so, the guage smooths out. The main volage gauge is jumping back and forth between 13 to 15 volts just as fast as the ammeter is bouncing.
From another thread, I changed out the voltage regulator and the ammeter and the voltage gauge is acting the same as before the swap.
Do I need to pull off my 1 year old alternator and have it checked?

Thanks


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144380
12/26/11 05:21 PM
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what alternator, and what voltage regulator?

that is, do you have a stock vr or the solid state?

is the alt stock, or a high amp model?

have you checked voltage at the battery when running?

have you checked voltage to the voltage regulator?
how about ground to the voltage reg?

Re: Ammeter/Main Voltage Fluctuating [Re: Andrewh] #1144381
12/26/11 05:38 PM
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Alternator is a Powermaster 75a unit (63a at idle and 93a total) and both voltage regulators are NAPA replacement units. The first VR is about one year old and the second one was bought last week.
The VR's were/are mounted on the firewall with a ground wire mounted off of each of the mounting bolts that go thru the firewall. Each of the ground wires go to different grounds in the engine compartment.
When I swapped to the second VR today and placed the positive wire from my multi meter on the positive side of the battery and then placed the negative wire from my MM on both of the VR mounting bolts and I got battery voltage. There is also a metal strip on the VR just below the connector and it also showed battery voltage. The body is definately grounded.
I did not check battery voltage at the battery or the VR with the engine running today. I just just watching both of my volt meters that are mounted inside of the car. One gauge is wired in to show battery voltage (switched) and the other is showing the battery feed voltage at my MSD unit. The battery voltage was fluctuating between 13-15 volts and the MSD 12v feed was fluctuating between 13.5-14.5. Both guages "average" 14.0 volts if that means anything.

Thank you for your reply.

Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144382
12/26/11 06:13 PM
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where are you getting the sensing voltage from for your vr?

as that signal passes through the bulkhead like 3 times in stock wiring.
did you see if that is plusing too?

Re: Ammeter/Main Voltage Fluctuating [Re: Andrewh] #1144383
12/26/11 06:51 PM
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I am using the stock wiring harness except that at the bulkhead, I had to bypass the blue wire around the bulkhead last year due to a burnt connector. Since the bypass, it ran fine all last year.
This came up on my last thread so I will throw it out there. I just installed a MSD ignition box and on the 12v switched feed to the MSD box, I connected three wires, the RUN blue wire (goes to the alternator/VR), the brown CRANK wire, and I also wired in the voltage guage that is showing a fluctuation of 13.5-14.5. These three wires are what is feeding the MSD 12v feed. I asked a MSD tech about wiring the voltage gauge in on the 12v supply and they said that it would be fine. I am not 100% sure on this as other board members have questioned it too.

Thank you.


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144384
12/27/11 07:14 AM
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On a difficult case like this one I'd use some jumpers directly: 8ga from alt to batt positive terminal (or starter relay), jumper from batt positive terminal to VE sense terminal. Jumper from batt to alt blue field wire male terminal. jumper from alt green field wire male terminal to VR side terminal. jumper from vr case to batt neg post and jumper from alt case to batt neg post. If it is now straight then remove 1 jumper at a time to pin down the offending circuit. If it's still acting up w all jumpers connected which is what I think it will be doing then that points to the alt. EDIT said VE but meant VR (voltage regulator)

Last edited by RapidRobert; 12/27/11 08:13 AM.

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Re: Ammeter/Main Voltage Fluctuating [Re: RapidRobert] #1144385
12/27/11 12:00 PM
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check the brushes in the alternator, and that the screws that holds the brushes are tight.

Re: Ammeter/Main Voltage Fluctuating [Re: cuda-sweden] #1144386
12/27/11 12:29 PM
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I have the old alternator that was working before I swapped in the higher amp unit from Powermaster. I might remove the PM unit and take it in for a test or swap in the old unit to see if I still get the voltage fluctuations.

Thanks allot.


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144387
12/27/11 01:22 PM
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also there is a square back that puts out 78 amps. 50 bucks at any auto parts store with a lifetime warranty.
just incase you get sick of dealing with powermaster warranties.

just look up an 89 new yorker full size.

Re: Ammeter/Main Voltage Fluctuating [Re: Andrewh] #1144388
12/27/11 04:46 PM
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I just found that 78a unit on the O'Reily web sight. I will pull this one and have it tested and then decide what direction to go.

Thanks allot


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144389
12/27/11 05:11 PM
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I guessing you'd want a stock looking alternator. But this denso unit off a Suzuki Samauri is awesome. Sooooo steady at low low rpm.

6986902-2_22_11Sm2.jpg (324 downloads)
Re: Ammeter/Main Voltage Fluctuating [Re: autoxcuda] #1144390
12/27/11 06:16 PM
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Quote:

I guessing you'd want a stock looking alternator. But this denso unit off a Suzuki Samauri is awesome. Sooooo steady at low low rpm.


details?? same brackets? what size belt? any alignment issues?

Re: Ammeter/Main Voltage Fluctuating [Re: autoxcuda] #1144391
12/27/11 06:23 PM
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If there is a problem with this PM unit, I am going to give them a chance to fix it. It puts out 63a at idle and with all of my lights on plus brakes, my ammeter never moved, until now. It is still under warranty and I am not driving the car right now, so I have some time.

Please give some info on the Denso unit. Does it mount the same as a stocker? What is the idle and the total amp rating. Where did you buy it?

Thanks to all.


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: mikemee1331] #1144392
12/27/11 06:45 PM
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Quote:

Quote:

I guessing you'd want a stock looking alternator. But this denso unit off a Suzuki Samauri is awesome. Sooooo steady at low low rpm.


details?? same brackets? what size belt? any alignment issues?




I used my 68 340 non a/c brackets. But the lower adjuster bracket was shortened a few inches. And there are spacers to align the V-groove pulley after mocking up with washers.

I drilled and tapped the alternator adjuster bolt hole to take a user friendly 1/2" hex bolt. Then the pivot stud holes where slightly drilled larger to take a std bolt into the block.

www.arengineering.com makes a nice bracket setup for this. And IMHO more stable than my setup.

I have a squeel in my setup under "pedal to the floor" acceration. Alternator may be a little too far out, or just puller groove too smooth, or need to change belt type/brand.




Last edited by autoxcuda; 12/27/11 06:49 PM.
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144393
12/27/11 06:59 PM
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Quote:

...

Please give some info on the Denso unit. Does it mount the same as a stocker? What is the idle and the total amp rating. Where did you buy it?

Thanks to all.




It's rated at 46-50 amp. Plenty for a car with no A/C, no p/w, high amp boombox stereo, etc... My car stock was rated with a 36 amp.

http://www.partsgeek.com/gbproducts/MC/1...eek+Google+Base

IIRC, I've seen them on Ebay for like $60 within the last year. If you moparts search my username and denso alternator I linked to the ebay seller that has/had them for a good deal.

Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144394
12/27/11 07:06 PM
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Quote:

If there is a problem with this PM unit, I am going to give them a chance to fix it. It puts out 63a at idle and with all of my lights on plus brakes, my ammeter never moved, until now. It is still under warranty and I am not driving the car right now, so I have some time.

Please give some info on the Denso unit. Does it mount the same as a stocker? What is the idle and the total amp rating. Where did you buy it?

Thanks to all.




I've heard some power master customers that have been unhappy. Especially for the big dollars they get for thier units.

Re: Ammeter/Main Voltage Fluctuating [Re: autoxcuda] #1144395
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Nippondenso 102mm

DB Electrical is where I found this alternator before: http://www.dbelectrical.com

Here's threads on how I hooked it up. I did not use a one wire unit. And I run it through my amp gauge. Very easy to wire. Especially on a 69 down early regulator type car.

https://board.moparts.org/ubbthreads/show...rue#Post6514733



https://board.moparts.org/ubbthreads/show...rue#Post6514626

Re: Ammeter/Main Voltage Fluctuating [Re: autoxcuda] #1144396
12/29/11 07:23 PM
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I took the Powermaster alternator to my local NAPA store today and it tested perfect on the machine. He said that the numbers could not have been better. He then tested my backup alternator and found it to be putting out too little voltage down low.
I put the alternator back on the car and I made some voltage checks with the key in the ON position. The battery was at 12.0, the alternator was 11,85, and the blue wire at the VR was 11.8, volts.
I am at a loss as to what to check next. I am going to review my wiring before the MSD swap to see what wires were being bypassed at my ballast before and see if I am missing something on my feed to the MSD 12v red wire.
Could I have an issue with the blue 12v wire/s that would cause the ammeter to fluctuate?
Thanks again,


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144397
12/29/11 08:24 PM
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did you ever track down that 'extra' brown wire? as a test move the MSD off the meter circuit and see if that changes the fluctuating. i know you wnat to monitor the MSD but just for a test sake to see if it's the MSD or the ballast wiring.

Re: Ammeter/Main Voltage Fluctuating [Re: mikemee1331] #1144398
12/29/11 08:46 PM
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The dual brown wire has 12v at crank and at run. I am thinking of adding this back in.
I will seperate the MSD 12v gauge to see if that helps too.
In the back of my mind, I am thinking of pulling the front harness and checking the wires for any issues. I hope that I don't have to do this but it is Winter and I could do it in the house.

thanks for the reply


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144399
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i just read a couple of articles on how a CD ingition works. it's entirely possible that the small red wire is pulling voltage in on/off cycles. what happens is the power charges a capacitor in the MSD. when that capacitor is 'full' it no longer needs voltage. as you rev the car, the cycles happen so fast that the guage can no longer keep up (visually)and the gauge looks to steady out. without seeing a wiring diagram of the insides of the unit i can't say for sure. i'm also not clear why the box requires 2 input voltages (heavy and small red wires).

Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144400
12/29/11 09:56 PM
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Have you checked the wire connections on back of your alternator guage on the cluster? They are known to lossen and give offset readings. I have fixed many with this issue in years past. Not saying that is your problem but doesn't hurt to check.

Re: Ammeter/Main Voltage Fluctuating [Re: 82ramIndy493] #1144401
12/30/11 11:16 AM
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I will check the back of the ammeter for a loose connection and I will disconnect the volt meter that is connected to the 12v MSD feed.
Thank you.

I took the attached picture back when I was running a ballast and the Mopar orange box. When I removed the ballast and added a 12v coil, I took all seven wires and connected them together and the car ran fne. Then when I swapped to the MSD box here a few weeks ago, I only used two wires, "single" brown (crank-not shown in picture) and blue (run) and the car starts and runs.
In the picture:
Light Brown: Crank/Ballast/Coil splice
Light Brown: Ballast to + coil
Green [Red tracer]: Un-used
Light Blue [Yellow tracer]: ECU to Run
Black [Yellow tracer]: ECU to - coil
Black: UNKNOWN
Blue: RUN
Not Shown: Light brown main feed for CRANK.

It appears that all three light brown wires are spliced from the same CRANK wire. I believe that I only need one which I currently have.
The blue RUN wire is required and currently wired.
The Green/RED, Light Blue/Yellow, Black/Yellow were coming off of the Mopar ECU and are no longer required.
The last wire that I do not have accounted for is the second Black wire shown in the picture.


EDIT:
The ammeter connections were tight and I changed the connection for the MSD volt gauge so that I can disconnect it and then reconnect it for a test.
I am going to wire in the blue run wire, the brown crank wire, and the double brown wires to the MSD 12v switched wire and the recheck the ammeter reading.
EDIT:
* I just found the connector for the 12v Blue-RUN/Brown-Crank to be "wiggle" loose. This feeds the 12v source for the MSD box. I "crimped" the male/female connector this time and there is no movement. Hopefully this may have been the issue. I will try and start the car this weekend to see what the ammeter is doing now. I will leave the 12v gauge disconnected at first then add it back in to see if there is a difference at the ammeter.
I also ran an external ground wire from the alt body to the battery negative ground wire just in case.

Thanks

6991768-ballastwiring.jpg (275 downloads)
Last edited by YO7_A66; 12/30/11 04:57 PM.
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144402
12/30/11 05:54 PM
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as much as a PITA it is, try and only make 1 change at a time!

Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144403
12/30/11 08:38 PM
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Quote:

I just found the connector for the 12v Blue-RUN/Brown-Crank to be "wiggle" loose. This feeds the 12v source for the MSD box. I "crimped" the male/female connector this time and there is no movement. Hopefully this may have been the issue. I will try and start the car this weekend to see what the ammeter is doing now.


Sounds promising I thought something was funny that the alt tested good (nothing loose inside) and I've never seen a solid state reg that caused that kind of fluctuation (point reg it absolutely could/would)


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Re: Ammeter/Main Voltage Fluctuating [Re: mikemee1331] #1144404
12/31/11 01:49 AM
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""try and only make 1 change at a time""
I usually try too but this time I have backed myself into a corner. We have 45 degree weather outside right now and in two days it will be in the 20's. So I am doing a few things together to try and find the issue.
thanks for the reply.

I hope that this loose connection was the issue since the alternator, ammeter connections, and two VR's checked out. I am still a little worried that one loose connector could make the ammeter jump this much. It was the BLUE-RUN wire connector though.
Thanks Robert.

Last edited by YO7_A66; 12/31/11 12:30 PM.

1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144405
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I charged the battery to about 80% and then started up the car without the volt gauge hooked up to the MSD 12v source wire.
At 1200rpms high idle, the battery voltage guage and the ammeter still fluctuated but not as bad. The voltage guage showed 14-15 and the ammeter moved from straight up to about 1/4" to the + side. It never showed discharge.
At 950rpms, the voltage guage showed about the same and the ammeter moved from straight up to about 3/8" to the right. So it shows worse still at a lower rpm.
The interior dash lights were changing brightness up and down too during the idle time but not at high idle.

What if the issue is something inside of the car and not in the engine compartment? Could a loose connection anywhere in the car cause the ammeter to fluctuate on the + side? If so, since the dash lights are fluctuating, should I track down that circuit to look for an issue?

Thanks again.


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144406
12/31/11 04:55 PM
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since none of this was happening before the MSD upgrade (right?) i would examine every circuit on every wire that you had to touch/change for the upgrade. i could very well be tied only to the interior lighting since the lights for your extra guages are probably tied to that curcuit. did you install the guages or were they there when you got the car?

Re: Ammeter/Main Voltage Fluctuating [Re: mikemee1331] #1144407
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Mike,
I do think that the dash lights were pulsating before the MSD swap but I do not recall if I noticed the ammeter/volt gauge fluctuating at that time. I added the dash light issue onto my Winter list a while back but I did not think about it being the issue of the ammeter until now. I have checked and rechecked the wiring for the MSD and I do believe that the MSD install is now good. When I saw the dash lights fluctuating today, that got me to thinking about the issue just before I parked the car for the Winter.
The guages are mine and I can trace the dash wiring fairly easily.

MSD Note:
I can already see the difference in how much easier the car starts with the MSD installed. The engine has started right up each time I have started the car even in the cooler outside temps. It will even startup without touching the accel pedal. I never had that with the orange box or the two FBO boxes.
Thanks for your reply.


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144408
12/31/11 06:02 PM
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i didn't think the 2 (MSD and jumpy guages) were ever related. just the keyed power source. i'm glad you like the MSD, you'll see a bit of a jump in throttle response off a light and better gas mileage. what kind of car are we talking about here, i've totally forgotten

Re: Ammeter/Main Voltage Fluctuating [Re: mikemee1331] #1144409
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It is my Challenger in my sig. I plan on chasing the instrument wiring to see what I can find and also checking the bulkhead connector just to make sure.

Thanks again.


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144410
12/31/11 10:15 PM
12/31/11 10:15 PM
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This is a long shot, but one time when I had my car serviced they returned it and the gauges were pulsing at a constant interval and I could also hear a little bit of noise behind the dashboard. I took it back the shop and they said it was probably a bad voltage regulator. I swapped out the VR and same problem. I was scratching my head because I could not figure it out. In desperation I started messing around with all the dials on the dash and it turned out to be the wiper delay switch was on or engaged in some funky mode where all the gauges were pulsing but the wipers were not moving. Once I turned the switch to off it quit doing it. This is most likely not your issue but I figured I would throw this out there if it was something you wanted to check. Hope you get it figured out. Keep us posted on what you find out.


70 Cuda 340 4 speed - now stroked to 416ci (SOLD)
2017 Mustang Shelby GT350
Re: Ammeter/Main Voltage Fluctuating [Re: loco340cuda] #1144411
01/01/12 11:44 AM
01/01/12 11:44 AM
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Loco,
Last night at 2am I read your response, I ran out to the garage and went directly to the wiper switch on the car. Crapt! That was not it! I was very hopefull though. Under the dash I go.
Thanks allot for your reply.

One thing that I thought of this morning was that when the key is in the RUN position but the engine is off, the battery volt gauge is steady. But when the car is running is when the gauges start fluctuating. I assume that this is due to the alt not charging and it means nothing.


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144412
01/01/12 01:10 PM
01/01/12 01:10 PM
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bethlehem pa
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Quote:

One thing that I thought of this morning was that when the key is in the RUN position but the engine is off, the battery volt gauge is steady. But when the car is running is when the gauges start fluctuating. I assume that this is due to the alt not charging and it means nothing.


does it show discharge when the key is in the accessory position? i think it should also show discharge when in the run position (engine not running) but i can't confirm that with my car in pieces

Re: Ammeter/Main Voltage Fluctuating [Re: mikemee1331] #1144413
01/01/12 02:45 PM
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YO7_A66 Offline OP
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I may have found one issue under the dash. I found a wire going into the headlamp switch with melted insulation. It is the pink wire. After I fixed the end, I turned on the headlights (all the way up) and I had lights but no parking lights. Then I tried the parking lights (mid position) only and I could not get the parking lights to light up until I pushed in on the switch and then they would flicker. It appears that I have an internal issue with my headlamp switch.
I know that they are not made new, so what are my options?

Thanks


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144414
01/01/12 09:47 PM
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i don't know what an E-body headlight switch looks like but i have pulled apart switches on my road runner before and clean them up. there is also a member who rebuilds them over in the 'hot new products' area. here's a link - https://board.moparts.org/ubbthreads/show...e=2&fpart=1

Re: Ammeter/Main Voltage Fluctuating [Re: mikemee1331] #1144415
01/01/12 10:33 PM
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Mike,
Thanks for the link. I have already pm'd him to see what options I have.

Thanks a bunch.


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144416
01/24/12 12:52 PM
01/24/12 12:52 PM
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My headlight switch ended up being good but my 12v feed wire to the switch was bad. It is fixed now.

Could a faulty battery cause the ammeter/battery voltage to fluctuate (13v-15v) if the rest of the electrical system is good?
Note: When I attach the (+) battery cable to the battery, I get a spark.

Thanks


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144417
01/24/12 08:51 PM
01/24/12 08:51 PM
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RapidRobert Offline
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Quote:

Note: When I attach the (+) battery cable to the battery, I get a spark.


Something is still on that shouldn't be, . Stay with it


live every 24 hour block of time like it's your last day on earth
Re: Ammeter/Main Voltage Fluctuating [Re: RapidRobert] #1144418
01/24/12 09:27 PM
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""Something is still on that shouldn't be, . Stay with it ""

CRAPT! Thanks Robert.

--------------------------------------------

""Could a faulty battery cause the ammeter/battery voltage to fluctuate (13v-15v) if the rest of the electrical system is good?""

I am going to have my battery checked tomorrow just to make sure.

-----------------------------------------------
I should have my new alternator from Powermaster this week and I have a new voltage regulator to test too.


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144419
01/25/12 02:16 AM
01/25/12 02:16 AM
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Valencia, España
NachoRT74 Offline
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how bigger was the spark ?

Did you have doors open ? trunk ? IGN switch in some position diff than OFF ?

do you have clock ? time delay flasher ?

if anything of that, mostly sure will spark, yes. bigger as far more equippment working


With a Charger born in Chrysler assembly plant in Valencia, Venezuela
Re: Ammeter/Main Voltage Fluctuating [Re: NachoRT74] #1144420
01/25/12 03:08 PM
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RE: MSD wires
The large red wire that is hooked directly to the battery is where the power for the MSD (charging the capacitor) comes from. As the capacitor charges basedd upon its discharge inot the coil it should be charging at 4 X rpm frequency which should be a lot faster than you can see.
The small red wire hooked to the ignition switch turns the box on or off. Current flow through this wire should be minimal.
R.

Re: Ammeter/Main Voltage Fluctuating [Re: dogdays] #1144421
01/25/12 09:59 PM
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I recieved my warranty Powermaster alternator. It is another 75a unit that shows as a 60a idle and a 99a total on the performance card.
I had my battery tested today and it checked 100% on life, so it is good.
I have a new AC Delco voltage regulator just in case the alternator does not fix the issue.
If this does not fix the ammeter/battery voltage fluctuation issue, then I might have to look into getting the MSD box reaplaced or looked at. I asked MSD if their box can create this ammeter/voltage issue and they said no. But I might look into a second opinion.

Thanks to all and I will test the alternator in the next couple of days when the weather allows.


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144422
01/26/12 01:35 AM
01/26/12 01:35 AM
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Valencia, España
NachoRT74 Offline
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Quote:

It is another 75a unit that shows as a 60a idle and a 99a total on the performance card.





that would be my dreamed alt!!!


With a Charger born in Chrysler assembly plant in Valencia, Venezuela
Re: Ammeter/Main Voltage Fluctuating [Re: NachoRT74] #1144423
01/26/12 01:31 PM
01/26/12 01:31 PM
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I received a PM from another member (thanks D B) that gave me the name of a company that works with MSD ignitions. I emailed their company with my current issue. They in return asked if I was running the BIG RED wire directly to the "+" battery post. He said that if I am running it thru a fuse from the battery post, then he has seen similar voltage issues.
Guess what? I am running a 40a fuse off of my starter solenoid (this replaced my original fusable link) and this BIG RED wire is connected at that fuse. This is also where my feed line connection is for my battery voltage guage inside of the car that is showing the 13-15v fluctuation. This is the same connection that my parallel bulkhead bypass wire is connected that leads to my ammeter. Both of these gauges are showing the fluctuation and I wired the BIG RED wire to that same connection.
(vendors description of why not to use a fuse: ""feedback produced by how the box draws current from the system, with a fuse inline this causes an oscillating effect that can drive you crazy trying to find"")
He said that it is a big no-no to run this BIG RED wire off of a fuse. I assumed that since the feed line for this fuse was fed from the starter solenoid which is fed from the main post on the battery, that it would have been fine for the MSD. I know that the instructions say to run directly to the battery post, which I did on the initial install. But to make the wiring look a little cleaner, I changed the connection point of this wire to mount at my main 40a breaker. My mistake!!
(But if I remember correctly, I tested the BIG RED wire on the "+" battery clamp and it did not make a difference. This is why I moved the wire back to my 40a fuse because it looked cleaner.)

I am going to stop by the parts store and pickup a battery cable that connects to the side post terminal with a small red wire attached. I will change this connection so the BIG RED wire connects directly to the "+ SIDE POST" on my battery. This way there is nothing else at that positive battery connection except for the MSD BIG RED wire. Then I will start it up and see what happens. With this change plus the new alternator, I sure hope to see a difference with my ammeter and battery voltage. I should be able to test it this weekend.

Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144424
01/26/12 05:03 PM
01/26/12 05:03 PM
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interesting


With a Charger born in Chrysler assembly plant in Valencia, Venezuela
Re: Ammeter/Main Voltage Fluctuating [Re: NachoRT74] #1144425
01/26/12 08:28 PM
01/26/12 08:28 PM
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bethlehem pa
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Quote:

interesting


very

Re: Ammeter/Main Voltage Fluctuating [Re: mikemee1331] #1144426
01/26/12 10:18 PM
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YO7_A66 Offline OP
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Techwest Racing is the company and they rebuild/modify MSD ignitions systems.
They appear to really know the MSD ignition systems. Checkout their websight, there is allot of info on there.
http://techwestracing.com/

Thanks again to D B for giving me the above info to share with the group.


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144427
02/02/12 10:21 PM
02/02/12 10:21 PM
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Update:
New alternator, moved the MSD Heavy Red wire to the side terminal on the battery. Started up the car and I still have the ammeter and the battery voltage gage fluctuating. The ammeter is bouncing even more than before. It is now dipping down into the "-" side about half way and then pegging out on the "+" side at idle. At high idle, the fluctuating guages are a little better, then when the rpms come up to 1500, the gages are fairly steady.
During high idle, I put my hand held volt meter on the battery and it read 15.1/15.2 (cold start, cranked it a few times, battery was not 100%). Then I brought the engine rpms down to idle and the battery still read 15.1/15.2 volts.
**The battery voltage is steady at idle and high idle.**
So while the ammeter and the battery voltage gage inside of the car are fluctuating badly at idle and medium at high idle, the battery still showed the same reading with my volt meter.
Why did does the battery show a solid reading when using a volt meter but the voltage gage inside of the car is fluctuating from 13-16v at idle rpms. Is my voltage gauge going out on me?

Note: The ammeter and the battery voltage are now fluctuating even worse (more rapidily) then before the alternator swap and the MSD wiring swap.
Note: Both the ammeter and the battery voltage gage are both hooked up to the same 40a fuse that is fed from the starter solenoid. This connection showed the same 15.1/15.2 voltage that the battery showed during idle and high idle. (This ammeter connection is the positive "parallel bypass" wire)

Do I test my next new voltage regulator? I am thinking that the current one is fine since the battery is showing 15.1/15.2 after cold startup and with a cold battery.

Something is screwing with my ammeter/inside battery voltage gage, but I am not sure what. Since they are both hooked up at the same 40a fuse, I am wondering if the volt gauge may be going faulty. Since I measure both sides of this fuse and they both read battery voltage, then the 40a fuse seems to be good. I am thinking of tracing the wires from the inside voltage guage to make sure nothing else is hooked up to it. Then if not, I might just remove the power going to this gauge to see if the ammeter still acts up.

My headlights did not dim at idle or high idle and the ammeter/voltage guage did not change while turning on/off the headlights. My dash lights fluctuated just slightly, but barely noticeable. They are much brighter after the alternator swap.

Bad voltage guage inside of car? Faulty wiring inside of car? Try new VR? Bad ground?

Any suggestions?

Thanks a bunch!!


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144428
02/02/12 11:12 PM
02/02/12 11:12 PM
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Eden, Texas
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Strawdawg Offline
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so what does the voltage read inside with the meter you used on the battery? Fluctuating, or not?

and it still sounds like the voltage sensing wire to the alternator is reading a volt lower than what the battery is seeing to drive the charge voltage up to 15


Steve
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144429
02/02/12 11:15 PM
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Might be a stretch to do but I'd take off the MSD & sub in the regular OE stuff & see if it's an MSD prob or how the system is reacting to the MSD stuff. Might also first unhook all charging system wires & jumper each system (including grounds) as I mentioned earlier to see if it's a wiring prob. Might lose that fuse also. we gotta back way up on this one I'm WAG ing here but that's what I'd do to get some progress tho you are working hard at solving this


live every 24 hour block of time like it's your last day on earth
Re: Ammeter/Main Voltage Fluctuating [Re: mikemee1331] #1144430
02/02/12 11:28 PM
02/02/12 11:28 PM
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BDW Offline
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Quote:

Quote:

interesting


very




I'd be very surprised to find a fuse would cause problems. It's nothing more than a wire?

Good luck

Re: Ammeter/Main Voltage Fluctuating [Re: BDW] #1144431
02/02/12 11:31 PM
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yeah that wouldn't make sense for the fuse to be doing it but I'd toss it all for a fresh start


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Re: Ammeter/Main Voltage Fluctuating [Re: Strawdawg] #1144432
02/02/12 11:38 PM
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The inside voltage guage was showing 13-16 volts (fluctuating real fast) while the hand held unit connected at the battery was showing 15.10 to 15.22 fairly slowly within that range.
Should I try the new voltage regulator?

I don't understand why one voltage gauge shows the 13-16 while the direct battery shows constant 15.1-15.2 at the same time unless the inside voltage gauge is going bad.

Robert,
My backup ECU is at FBO being rebuilt. I sure hope that the MSD is not causing this.

I could remove the fuse but both studs showed the same 15.1-15.2 which was the same as the battery voltage.

Thanks for the replies.


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144433
02/02/12 11:49 PM
02/02/12 11:49 PM
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If you inside gauge is analog (has a needle) and your hand held is digital (numbers) then the hand held will not react fast enough to fluctuate like the gauge.

You should always take an electrical load off the alternator output stud, not the battery post.

I'll bet your MSD is making hr gauge jump around as it's a heavy draw that is constantly turning on and off.


They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.
Re: Ammeter/Main Voltage Fluctuating [Re: Supercuda] #1144434
02/03/12 08:43 AM
02/03/12 08:43 AM
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Super,
You are correct. My inside gauge that is hooked up to show the battery voltage is a "cheapo" gauge with a needle. My hand held unit is a one month old digital.
Does this mean that I should upgrade my inside voltage gauge to a digital unit?
I could try using the hand held digital unit inside of the car and hook it up to the existing voltage gauge to see what that 13-16 fluctuating reading smooths out to on my hand held unit.

That would be nice if this is just an issue with my cheap needle gauge. But then my ammeter would always be fluctuating, and this MSD5 unit is only supposed to pull .7a at idle.
Or, would the digital voltage guage "dampen" what the ammeter is reading since they are both connected to the same 12v feed?

I currently have an email in to Techwest Racing to see if they can give me a way to test the MSD5 unit on my car to rule that box out as a possible issue or not.

If 15.1-15.2 at the battery is too much, then is there anything else besides the VR that could make it charge this high? I have a new AC Delco voltage regulator waiting to go on if needed. My current VR is an Echlin unit and the previous one was the same model number. Both Echlin units made the same reading on the inside voltage gauge.

Thanks for the reply.

Last edited by YO7_A66; 02/03/12 10:14 AM.
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144435
02/03/12 11:09 PM
02/03/12 11:09 PM
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davenc Offline
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Y07_A66:

The analog gauge may show fluctuations that the digital gauge does not, depending on how the digital gauge is making its measurement. For giggles, you could connect your digital gauge probe to the same wire going to the analog gauge.

What is the rate of fluctuation of the ammeter? Does the gauge spend about the same amount of time in either position, or does it spend more time in one of the two positions?

Is the behavior of the ammeter fluctuation similar to sound of the turn signal flasher? If you want to try a wild experiment, remove both flashers (turn signal and emergency) and disconnect the black wire from the back of your temperature gauge and see if the problem still persists.

This is a wild guess but to me it sounds that there is a high resistance short on a voltage wire that turns on and off (hence the change in current draw seen on the ammeter). I believe there are 3 such things in your dash: your 2 flashers and the voltage "regulator" for the instrument panel. Granted, the flashers should not typically be energized, but let's be cautious.

Dave

Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144436
02/03/12 11:13 PM
02/03/12 11:13 PM
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Quote:

If 15.1-15.2 at the battery is too much, then is there anything else besides the VR that could make it charge this high? I have a new AC Delco voltage regulator waiting to go on if needed. My current VR is an Echlin unit and the previous one was the same model number. Both Echlin units made the same reading on the inside voltage gauge.




I didn't read the rest of the thread, but to me, 15.1-.2 is too high. I bet the blue wire at the alternator is .6-.7v lower than the battery voltage, causing the regulator to pump the voltage that much higher. This is caused by the resistance in the connections between the battery and the blue wire (bulkhead, etc).

You can measure this difference, and if you jump the battery + directly to the blue wire at the alternator, you should go back to 14.5ish at the battery.

Have to go now, but I can post a diagram later if that would help.


If you ever find yourself in a fair fight, your tactics suck.
Re: Ammeter/Main Voltage Fluctuating [Re: davenc] #1144437
02/04/12 11:50 AM
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""What is the rate of fluctuation of the ammeter?""

The ammeter needle moves fast from one side to the other. It is constantly moving fast and it slows down as the rpms come up into the mid teens.
It does not match a turn signal pattern, it just fluctuates thru about 70% of the ammeter range, quickly.
I will turn on the turn signals and the emergency flashers to see how they act. All of the dash gauges work and act normal.

Thanks for your response


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: hooziewhatsit] #1144438
02/04/12 12:00 PM
02/04/12 12:00 PM
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""I bet the blue wire at the alternator is .6-.7v lower than the battery voltage, causing the regulator to pump the voltage that much higher. This is caused by the resistance in the connections between the battery and the blue wire (bulkhead, etc).""

I have already had to bypass the blue wire around the bulkhead last year. I will try and trace the blue wire and ispect the connections.

""You can measure this difference, and if you jump the battery + directly to the blue wire at the alternator, you should go back to 14.5ish at the battery.""

Do you mean to "disconnect" the blue wire at the alternator, or add an additional wire from the same alternator blue field wire over to the "+" battery cable and start the engine?
Then measure the voltage again at the battery and at the alternator to see if they match? If they match and if the battery voltage is now lower, then the blue wire connections is the issue?

Thanks for your reply.
It will be a few days before I can get back on this but I will add this to my hit list.


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144439
02/04/12 04:08 PM
02/04/12 04:08 PM
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Strawdawg Offline
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I was trying to get you to use the meter that you checked across the battery with to check the voltage at the point your inside gauge is connected to. As others have said, an analog gauge may react differently than a digital gauge but it would be nice to know.

I would guess your MSD switching is causing the flick, but, nothing like proving it.

And, unless your regulator is bad, I would still suspect your blue wire is reading a lower voltage than you are seeing at the battery with the meter.


Steve
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144440
02/04/12 04:16 PM
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Quote:

""I bet the blue wire at the alternator is .6-.7v lower than the battery voltage, causing the regulator to pump the voltage that much higher. This is caused by the resistance in the connections between the battery and the blue wire (bulkhead, etc).""

I have already had to bypass the blue wire around the bulkhead last year. I will try and trace the blue wire and ispect the connections.

""You can measure this difference, and if you jump the battery + directly to the blue wire at the alternator, you should go back to 14.5ish at the battery.""

Do you mean to "disconnect" the blue wire at the alternator, or add an additional wire from the same alternator blue field wire over to the "+" battery cable and start the engine?
Then measure the voltage again at the battery and at the alternator to see if they match? If they match and if the battery voltage is now lower, then the blue wire connections is the issue?

Thanks for your reply.
It will be a few days before I can get back on this but I will add this to my hit list.




I think I left the blue wire hooked up with a spade terminal splitter thing and started it. With the DMM hooked up I had ~15.5v. I hooked up the jumper and it immediately dropped to 14.5ish, verifying that was my issue. You can also put the negative lead of your DMM on the blue wire, and the positive lead on the battery +. That voltage should ideally be 0v. Whatever voltage you do read will be how much higher the battery charges than it would otherwise.

Also, if you leave the jumper hooked up, it will not turn off with the key

You can also hook up the jumper then start it, but don't let it sit there long without running; it's just like having the key on Run without starting it. In theory the points/coil could burn up.


I ended up installing a relay triggered by the blue wire to provide power directly to the regulator/alternator.


If you ever find yourself in a fair fight, your tactics suck.
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144441
02/04/12 06:42 PM
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Quote:

I am using the stock wiring harness except that at the bulkhead, I had to bypass the blue wire around the bulkhead last year due to a burnt connector. Since the bypass, it ran fine all last year.
This came up on my last thread so I will throw it out there. I just installed a MSD ignition box and on the 12v switched feed to the MSD box, I connected three wires, the RUN blue wire (goes to the alternator/VR), the brown CRANK wire, and I also wired in the voltage guage that is showing a fluctuation of 13.5-14.5. These three wires are what is feeding the MSD 12v feed. I asked a MSD tech about wiring the voltage gauge in on the 12v supply and they said that it would be fine. I am not 100% sure on this as other board members have questioned it too.

Thank you.






You answered your question here. You had to by-pass a burned connection. You fixed one, you probably have atleast one more.

I had the same problem on a 71 Challenger R/T. The ammeter gauge would discharge a little at idle, not much, but when I'd rev the engine or drive, the needle would go way up. I changed voltage regulaters, alternators, added grounds, did who knows what all. Still no solution. I actually cooked the battery one or two times. Litterally blew the caps off of it. Had it to a few shops and no one could find it.

One day I was messing around looking under the dash and noticed a black streak in the steering column to main harness connection. I tried to pull it apart, but couldn't. So I cut the wires and spliced the two together. From that point on, the car charged correctly.

Keep looking for a burned connection somewhere!

Re: Ammeter/Main Voltage Fluctuating [Re: 70HemiGTX] #1144442
02/04/12 07:36 PM
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I am thinking of pulling the front engine harness out of the car and inspecting all of the connections. Then tape it back together after replacing as much of the blue wire that I can find. Then retape it back into a harness again once I am sure that it is in good shape.

I am also going to check the green wire going from the VR to the alternator for any resistance.

Thank you all for your help.


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144443
02/05/12 01:45 PM
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I just pulled the VR connector loose and made a continuity check on the green wire (VR to alt) and it showed .3/.4 ohms.
What does this tell me? Is this too much? If so, I will cut this wire out and splice in a new one.

I am now looking at the blue wire where I bypassed the bulkhead.

Thanks


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144444
02/05/12 01:52 PM
02/05/12 01:52 PM
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hooziewhatsit Offline
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Touch your two meter leads together and see what their resistance is (probably .1 or .2). Then deduct that from whatever you measure.

A run as short as the green wire should be dang near 0ohms.

Another good way to test is to measure the voltage drop under load.


If you ever find yourself in a fair fight, your tactics suck.
Re: Ammeter/Main Voltage Fluctuating [Re: hooziewhatsit] #1144445
02/05/12 02:15 PM
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My leads showed 0.0 before I took the above reading.

I reviewed my connections for the MSD 12v source and this is what I had:
Blue Run
Brown Crank
MDS Small Red
Voltage Gauge wire (this is my second inside voltage guage to watch my 12v source to the MSD from inside of the car)
(2) Brown wires from previous ECU setup that showed 12v during Crank and Run.

I just removed the two Brown wires that used to feed the ballast and now I just have the MSD Red, Blue, Brown, and voltage guage at that connection.

I am going to follow my blue wire next.

thanks for the reply.
Should I replace the green VR wire?


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144446
02/05/12 04:18 PM
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I changed a couple of the connectors on the Blue wire/White tracer that goes from the bulkhead to the alternator.
I started up the car and the ammeter and battery voltage are still fluctuating at idle (wild)and at high idle (1200rpms) the ammeter is only in the "+" and my inside voltage gauge shows 14-16v and at 1500rpms the ammeter and voltage reading is solid.

At high idle, I took a voltage reading at the battery and it showed 15.1-15.3 and at the alternator main stud showed 15.2-15.5 volts.
Since they are both showing approximately the same reading (still high), what does this tell me? Is this showing a VR problem?

Does the .1-.2 ohm reading on the Green wire from the VR to the alternator seem like an issue?

Turn signals and Hazzards are acting fine.

thanks again.
Now I am going to start looking behind the dash.


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144447
02/05/12 05:43 PM
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I still say you have a bad connection on one of your "heavy" main power wires. That is what is causing your alternator to work harder. Some where you have a poor connection. Trace all of your heavy red wires under your dash, up the steering column, and out to the starter relay.

Re: Ammeter/Main Voltage Fluctuating [Re: 70HemiGTX] #1144448
02/05/12 05:53 PM
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I now have the dash panel off that has the headlight switch/wiper switch and also the main gauge cluster off and I do not see anything obvious. The ammeter studs are tight and tomorrow I will check the ammeter wire connections. Then I will work around the fuse block, then the steering column connector, then out at the starter relay.

Thanks again.


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144449
02/05/12 06:02 PM
02/05/12 06:02 PM
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jumping across various points may help you find a circuit of high resistance if you hit one that straightens it out. I'm rootin for ya


live every 24 hour block of time like it's your last day on earth
Re: Ammeter/Main Voltage Fluctuating [Re: RapidRobert] #1144450
02/06/12 04:55 PM
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I checked the ammeter wiring and it was tight. I checked all of the wiring for the headlight switch and the wipers and all was good. I pulled both of the connectors on the steering column and they were all clean. I looked under the dash for other issues and did not find anything obvious. I did find a loose connection at the accessory feed that goes to my electric choke and I tighten that up. But I found nothing that showed a loose connection.

I know from yesterday that the green wire at the VR-Alt showed a continuity check of .4ohms.
Today, after I got the dash put back together, I turned the key to the "RUN" to check the voltages at the battery, VR, and at the field wires of the alt:
Bat: 12.1v
VR: Both green and blue showed 11.9v
Both Alt Field wires showed 14.1v!!!!

How in the He99 can I get a reading at the alt field wires that showes a voltage 2v higher than the VR and the battery feed with the engine off????? (Engine off, key at the RUN position)
Do I have an electrical transformer under my hood?

Thanks


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144451
02/06/12 05:02 PM
02/06/12 05:02 PM
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Techwest Racing shows a test for MSD ignitions as shown"
"" How to check Your Msd Ignition Box For Damage For the Racer who feels they have a failed MSD®Ignition, there is a simple test that TechWest Racing Services can walk you through to confirm a true failure of your MSD®Ignition.

First you will need a Volt/Ohm meter (this check can be performed with an analog or digital meter as well). The type of meter will not change the outcome of the test performed. Set your volt/ohm meter on the 1k ohms scale, then position the MSD®Ignition in approximately the same orientation as mounted in the vehicle. This is done to ensure that the MSD®Ignition is relatively in the same position as when the failure occurred. Next take either lead and attach it to a bare metal area on the MSD®Ignition. The second lead needs to be hooked to the Large Red wire that provides your main 12vdc input. In an Undamaged MSD®Ignition the needle will stay in the home position (ie. max Ohms for scale chosen). A Damaged MSD®Ignition will show a reading of 3k ohms or lower.

The readings mentioned above are the result of our experience with repairing customers MSD®Ignition systems. If you plan on testing your MSD®Ignition while it is still mounted in your vehicle PLEASE remove the LARGE RED wire (ie. main 12vdc). Failure to do this will result in possibly damaging your meter while performing this test on your MSD®Ignition.""

What do you think?
Removing the BIG RED wire from the battery and checking continuity in the box? How would this hurt a meter?

Thanks


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144452
02/06/12 06:36 PM
02/06/12 06:36 PM
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Quote:

What do you think?
Removing the BIG RED wire from the battery and checking continuity in the box? How would this hurt a meter?




It sounds like the test is measuring the resistance from the power input to the case ground on the MSD. Ideally there would be no connection. If it measures 3k or lower, there's a connection to ground internally (which apparently is a bad thing).

I'm not quite sure how it could damage the meter, but I would agree it would be best to disconnect the input before doing the test. Otherwise, you're also measuring the resistance to ground of any other device that's also hooked to the battery + terminal.




Quote:

Bat: 12.1v
VR: Both green and blue showed 11.9v
Both Alt Field wires showed 14.1v!!!!
How in the He99 can I get a reading at the alt field wires that showes a voltage 2v higher than the VR and the battery feed with the engine off????? (Engine off, key at the RUN position)
Do I have an electrical transformer under my hood?




What were you measuring when you say the Alt field wires? Those should be the same as the green and blue wires. Otherwise, I have n idea how you measured 14v


If you ever find yourself in a fair fight, your tactics suck.
Re: Ammeter/Main Voltage Fluctuating [Re: hooziewhatsit] #1144453
02/06/12 08:01 PM
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""What were you measuring when you say the Alt field wires?""

Hand held meter: black on ground and the red on each field wire (one at a time) to measure the voltage at the alternator with the key at RUN, VR connected.
I was expecting to see the same voltage that the VR showed but I was confused when I found the 14v reading. I turned off the key and thought about it then I made the same test again and found the same 14v reading.
I don't understand how it can show 14v at the field wires (VR connected)when the blue and green wires at the VR (disconnected from the VR with the key on) gave me 11.9v.

Last edited by YO7_A66; 02/07/12 08:20 AM.

1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144454
02/06/12 11:14 PM
02/06/12 11:14 PM
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Danny Offline
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A friend of mine was experiencing the same problems you are having, he also had msd box. He was pulling his hair out trying to find the problem. This past weekend he switched to mopar performance igition with orange box and fixed his problem! He also bypassed ballast resistor. Not sure if that is a good idea but he read in mopar muscle it was ok.?

Re: Ammeter/Main Voltage Fluctuating [Re: Danny] #1144455
02/07/12 08:26 AM
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My reasons for trying the MSD was due to the failures of the orange box and the FBO box.
I will check the MSD box continuity tonight as described in the above thread to see if that is an issue or not.

So how can my alternator field wires be showing 14.0v (VR connected) when the green and blue wires at the VR (disconnected) are only showing 11.9v and my battery is at 12.1v with the key at the RUN position, engine off?
Does the VR raise the voltage going to the alternator?
What else could cause the voltage to go up when the key is at the RUN position, engine off?

Note: I was discussing this with an EE at work this morning and he suggested that I pull the LARGE RED wire from the MSD box off of the battery and then recheck my alternator voltage to see if it goes back down to 12v. He also suggested that if it does, then to try diodes on the LARGE RED wire and the SMALL RED wire (crank/run). If the MSD box is creating the extra voltage, then stopping the voltage from "leaking" may help.

EDIT:
Fact: The blue wire with a white tracer runs from the alternator field wire thru the bulkhead and up the steering column. I then "assume" that it goes to the ignition switch.

The MSD SMALL RED wire is connected to the CRANK and the RUN wires, which are both coming from the ignition switch. If there is feedback (or extra power) thru the SMALL RED wire from the MSD box that is going back thru the RUN circuit, then it appears that it could make it out thru the blue/white wire to the alternator. So in the RUN mode, that might be where the extra voltage is coming from to make the field wire show 14v with the key in the RUN position.

Does this make sense? I am waiting on MSD to clarify if there is any extra voltage coming from the box during the RUN mode.

EDIT 2:
This is the response from MSD when I asked if the MSD box can add additional voltage thru the small red wire:

""Realize that the gauge is 40 years old, you may just have a faulty gauge or a gauge that needs to be reconditioned and updated for a modern, higher current output application such as when the MSD is installed. The older gauges were not engineered or designed for the high voltage and current of a CD unit.

The other possibility is that the gauge is being affected by the multi-spark function of the ignition. The multi-spark function actually fires the plugs multiple times during each firing event at rpm's up to 3,000 rpm.

If it were my vehicle, I would seriously consider having the amp gauge looked at and upgraded.""
-------------------------------------------------------------------------------------------------------------------------------------

I can't see how an old ammeter or a multi-spark ignition can cause the alternator voltage to go up 2v with the engine off.
I am going to add a diode on the small red wire to see that stops the extra voltage.

Thanks a bunch!!

Last edited by YO7_A66; 02/07/12 01:32 PM.

1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144456
02/08/12 12:25 AM
02/08/12 12:25 AM
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davenc Offline
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"Does the VR raise the voltage going to the alternator?"

I readily admit that I have not paid much attention to how the automotive VR works inside, but it needs to alter the voltage to the alternator field in order to control the output of the alternator. If the VR was only able to trim the battery voltage then it would not be able to increase alternator output when the battery voltage was low. So in answer to your question, the VR *can* raise the voltage going to the alternator field.

In your experiment the engine was not running and the voltage was at 11.9. Given that the VR is designed to keep the system at 14.5V, it makes sense that a higher voltage would be presented on the field circuit.

In my opinion, the MSD by itself is not causing the problem, although it still makes sense to do the test you described (in an earlier post you asked why to disconnect the heavy red from the battery before the test; I would do this just to be safe). I run a 6AL-2 and do not experience anything like what you describe. In my car I could notice a definite difference in the load on the electrical system after installing the MSD because my ammeter is now always a bit farther on the charging side (ie alternator is needing to deliver more current due to the extra load) as compared to when I had a chrome box on the car.

I don't have a great suggestion at the moment. I continue to think that there is some sort of high resistance short somewhere in the system. You will likely just need to take a very methodical approach to debugging it. One thing you may want to consider is pulling every fuse that is not absolutely necessary. You could also jumper over the ammeter with a heavy gauge wire and just use the analog voltmeter to see if the condition persists.

Re: Ammeter/Main Voltage Fluctuating [Re: davenc] #1144457
02/08/12 08:17 AM
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I should also say, when my buddy put the msd in his cuda a couple years ago it was fine. His problem suddenly started one day and he tried everything, checked everything, bypassed ammeter guage, tried three alternators, two voltage regulators, swapped coils, pulled every fuse one by one. He thecked all grounds, he went crazy trying to figure it out. THEN,he put all original parts back on, (alt, volt reg,coil) and ditched msd and went with new orange box and all is well. Sounds crazy?

Re: Ammeter/Main Voltage Fluctuating [Re: Danny] #1144458
02/08/12 09:06 AM
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Dave,
""In your experiment the engine was not running and the voltage was at 11.9. Given that the VR is designed to keep the system at 14.5V, it makes sense that a higher voltage would be presented on the field circuit.""

* Is it normal for BOTH field wires to show 14+ volts or would one field wire show it and the other would not?
Thanks


Danny,
That does not sound crazy and that is exactly what I am going thru. Thank you.


Before I tested adding the diode, I rechecked my voltages again with the key in the RUN position and the engine off. I once again found 14.5-15.5v at "both" of the alternator field connectors while just 12.0v at the battery and 11.9v at the MSD SMALL RED (CRANK/RUN) wire. At the least I am only losing .1v from the battery to the MSD box (CRANK/RUN) connection.

Then I added the diode (400v/1.5a, this does not allow feedback into the CRANK/RUN circuits) on the MSD SMALL RED wire last night and I made some more tests. Now with the key at the RUN position and the engine off, I was getting a voltage reading at the alternator BLUE wire of 11.9v and the GREEN wire of 1.1v. I could not get a reading of more than 11.9v at the BLUE wire after three different attempts (shutting off the key, waiting a few mintues, then testing again). I did not get a chance to start the car but at least my voltages are down.

The theory here is that the Street Fire box (economical street box) may have feedback thru the SMALL RED wire that is connected to the RUN/CRANK 12v feed wires that lead to the key. (Maybe the MSD 6 and 7 boxes do not do this) The key is also connected to the alternator field wire thru the BLUE/WHITE TRACER wire. If the MSD SF box is "leaking" due to the internal capacitors, then it appears that the voltage could be affected all the way back to the alternator. This is why I am testing a diode on the MSD SMALL WIRE to keep any "leaking" from exiting the MSD box and into the CRANK/RUN wires. (see attached)

Note: MSD suggested that I upgrade my current 40 year ond ammeter and my cheepo inside voltage gauge to new Autometer units. MSD said that they talked to Autometer about this which resulted in this suggestion. I wonder if the Autometer gauges already have diodes in them to keep the feedback out of the gauges.

I also made a continuity check on the MSD LARGE RED wire to the MSD housing and got a 0.0 reading. So that looks good.


I won't be able to start the car for a while due to our weather but I just want to see if the battery/alt voltage drops down from 15+ and also to see if the ammeter fluctuation changes.

It is a shot in the dark but I want to try it.

Thanks for the replies.


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144459
02/09/12 12:02 AM
02/09/12 12:02 AM
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davenc Offline
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>>>> Is it normal for BOTH field wires to show 14+ volts or would one field wire show it and the other would not?

Well it seems I missed this point earlier. That does indeed seem odd. I wish I could try on my car, but the motor is apart and the battery out. I also realize that I have replaced my under hood harness some years ago so it may not be fair to make apple-to-apples comparisons with.

It is very interesting that your diode experiment changed the results, and perhaps you are on to something. In thinking about it more and looking at the wiring diagram, it seems clear my previous response is wrong. I'm not certain but I suspect what happens with the dual field alternator is that system (battery) voltage is on one field wire (blue) and the VR alters the voltage on the second field wire (green). It may be the difference between these two voltages which controls the output of the alternator. In a single field, the VR alters the voltage on the one field wire and it is the difference between that and ground which controls the output.

If the above is correct, then you latest measurements on the fields make sense. However, this does not explain why earlier you had high voltage on both fields. The voltage on the green wire should be controlled from the VR; if the VR made that voltage match the blue wire (btw, on my car it is solid dark blue and solid dark green that go to the alternator field), then there would be 0V difference, which I think means the alternator would have no output which does not make sense. Even if the MSD is somehow raising the voltage on the blue wire, I don't understand why the green would also go up. Please don't take any of this as gospel because I am not completely certain.

Is your car a 70? Do you have a 2 or 4 prong ballast? Do you have a dark blue instead/in addition to a blue with white tracer?

Re: Ammeter/Main Voltage Fluctuating [Re: davenc] #1144460
02/09/12 09:24 AM
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YO7_A66 Offline OP
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YO7_A66  Offline OP
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Joined: Jan 2003
Posts: 5,442
Indiana
Dave,
My car has a Blue/White tracer wire from one of the field wires all the way back thru the bulkhead and up the steering column then it disappears going to the key switch. This is a 70 car with an 8 year old YO wiring harness and the ballast is removed with the MSD swap.

This is interesting, In the MSD kit, they provide a 100v/1a diode in the case of RUN-ON. MSD told me that I do not have run on so this is not my problem. But, if MSD provides a diode for RUN-ON and a diode keeps voltage from going backward thru a circuit, then the main cause of the RUN-ON is due to the box leaking back into the run circuit which is what I believe that I am experiencing.

The only guess that I can come up with on the 14+v on both field wires is the system appears to be "holding" a charge for some reason. The only theory that I have is that the box is leaking back thru the RUN circuit and it stays charged in the system. Once I completely disconnect the battery, then I can put a test light in-between the battery cables and the battery and my test light will light for a second and then slowly die out. Then I can put the battery cables onto the battery without a major spark. If I do not do this with the battery, then when I put the battery cables onto the battery I get a pretty good spark. I started a thread a few weeks ago about the spark at the battery and at that time, the MSD was not a suspect.
If the diode is the fix, this is not a major deal since a proper sized diode comes with the kit. This may not even affect those who run with a newer ammeter and newer digital guages.

Thank you again for your response. I won't know for sure if the diode helps my ammeter/analog voltage gauges until the weather warms up enough to start the car.


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144461
02/18/12 10:39 AM
02/18/12 10:39 AM
Joined: Jan 2003
Posts: 273
WV
D
Danny Offline
enthusiast
Danny  Offline
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Joined: Jan 2003
Posts: 273
WV
any updates?

Re: Ammeter/Main Voltage Fluctuating [Re: Danny] #1144462
02/18/12 05:16 PM
02/18/12 05:16 PM
Joined: Jan 2003
Posts: 5,442
Indiana
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YO7_A66 Offline OP
master
YO7_A66  Offline OP
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Joined: Jan 2003
Posts: 5,442
Indiana
Danny,
Thanks for asking and yes, I just got in from the garage.
After adding the diode on the MSD small red wire (where the CRANK/RUN/#2 inside voltage gauge are all connected) I now have NO MORE FLUCTUATING AMMETER AND BATTERY VOLTAGE AT IDLE!!!!!!!!!

This has been a long and drawn out issue but it came down to a $1 diode that is now keeping the voltage from the MSD unit from affecting the RUN circuit. At my idle rpms, my MSD CRANK/RUN voltage is steady and my battery feed is now steady and my ammeter is now steady AGAIN!!!!!!!!!! My battery is now showing 14.8v instead of 15.2 during high idle. So apparently my first and second voltage regulator are good too.

I will update my MSD5 Street Fire thread once I get the schematic updated.
I need to point out that the Street Fire box never missed a lick during this issue. It was all in the way that the two inside voltage gauges and the ammeter were fluctuating after the install. The only two things that I did different from the MSD wiring schematic, were adding a voltage gauge at the MSD SMALL RED WIRE/RUN/CRANK connection so that I can watch the ignition feed voltage from inside of the car, and I added the diode at the end of the MSD SMALL RED WIRE before it connected into the supply voltage/voltage gauge.
I mapped out the RUN/CRANK circuits along with the parallel ammeter wire upgrade and I was surprised how much of the circuits were affected by this feedback issue. I will post that schematic on Monday when I have it in front of me. After all of this, it appears that the ammeter and my cheap mechanical voltage guages mixed in with an external alternator voltage regulator are all to blame. I have read where alternators with built in regulators help absorb this feedback and also newer digital ammeter/voltage guages also help absorb this type of feedback.
I am a little disappointed with the MSD tech websight. After explaining all of what I have done on this thread, before I sent in my Powermaster alternator for the test, they told me that the small red wire would not cause my ammeter or voltage gauge issues. This is the main reason why I sent in my alternator to Powermaster. I asked MSD if the diode in the kit might help this and they said no since I was not having any RUN-ON issues. Since it is Winter and I have not driven the car since the install, my guess is that I would have had RUN-ON issues once the motor was up to driving temp.

Now I can install my new vacuum advance distributor!!!!!

Thanks again to everyone that kept with me on this issue. Now I need to write an apology to Powermaster letting them know that the problem was never the alternator that they replaced for free six months out of warranty.

Thanks again

Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144463
02/19/12 11:20 PM
02/19/12 11:20 PM
Joined: May 2005
Posts: 598
NC, USA
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davenc Offline
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davenc  Offline
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Joined: May 2005
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NC, USA

That's great news that the problem is solved!

I wish I understood better exactly what was going on though. It seems the Streetfire unit was back powering the run circuit with a stepped up voltage for some reason.

Dave

Re: Ammeter/Main Voltage Fluctuating [Re: davenc] #1144464
02/20/12 08:48 AM
02/20/12 08:48 AM
Joined: Jan 2003
Posts: 5,442
Indiana
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YO7_A66 Offline OP
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YO7_A66  Offline OP
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Indiana
I attached a sketch that I made showing "some" of the circuits that I think were affected by the feedback.
During the RUN mode, the ignition switch feeds 12v to most, if not, all of the car circuits. This sketch shows how the RUN circuit is connected to my ammeter, the MSD ignition feed voltage gauge, and the battery voltage gauge which were all being affected.
Once I drew it up, I could see how each one was being affected and the sketch just kept getting bigger, so I stopped. My dash lights were also fluctuating but I started to run out of paper so I stopped mapping it out.
But once again, the $1 diode which comes in the kit seems to have fixed the feedback issue.


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144465
02/20/12 11:33 AM
02/20/12 11:33 AM
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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RapidRobert Offline
Circle Track
RapidRobert  Offline
Circle Track
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
Quote:

the $1 diode which comes in the kit seems to have fixed the feedback issue.


that wasn't too bad now was it . Glad ya got it


live every 24 hour block of time like it's your last day on earth
Re: Ammeter/Main Voltage Fluctuating [Re: YO7_A66] #1144466
02/20/12 06:22 PM
02/20/12 06:22 PM
Joined: May 2005
Posts: 598
NC, USA
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davenc Offline
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NC, USA
I can't read everything on the wiring diagram you made, but notice that there appears to be other modifications around the ammeter. Not that it matters now, but I am curious if you ever tried the system without this modification in place? What is the intention of those changes?

Re: Ammeter/Main Voltage Fluctuating [Re: davenc] #1144467
02/20/12 09:06 PM
02/20/12 09:06 PM
Joined: Jan 2003
Posts: 5,442
Indiana
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YO7_A66 Offline OP
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YO7_A66  Offline OP
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Joined: Jan 2003
Posts: 5,442
Indiana
The sketch was only made for my notes at the time, so that is why it is so messy.
I did the ammeter parallel wire bypass upgrade to relieve some of the amperge thru the bulkhead connector. I feel safer with this wiring change with the higher amp alternator. This change was done before this issue came up.

Thanks dave.

Robert,
This one kicked my butt!!

-----------------------------------------

EDIT:
Since I have posted this response, I have started up the car several times and the ammeter and both voltage guages are rock-solid at idle. The diode on the small red wire worked great.
Note: If you experience engine run-on or any voltage fluctuations with the MSD box, please consider using the diode that comes in the kit on the small red wire.

Last edited by YO7_A66; 03/01/12 08:45 AM.

1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
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