Moparts

Need advice on electrical issue

Posted By: Fab64

Need advice on electrical issue - 10/18/14 06:56 PM

Hi all,

I recently bought a '71 Satellite that seems to have a few electrical issues. In the first pic, you can see an inline fuse on the green wire. I don't know if this is stock or not(?). The PO told me he always disconnected it when parking, to avoid any problems. I soon found out why. When it's connected, it will drain the battery in about 4 days.




So, I began disconnecting it while the car was parked, and figured I could live with that, at least for awhile. However, I recently realized that this wire and fuse are getting very hot to the touch when I drive the car, even after only a few minutes running. This concerns me as I certainly don't want to burn up my wiring loom (which happened to me in a '69 Dodge van many years ago). The other end of this wire goes into the junction block at the firewall. In the pic below, it is the top-most black wire which curves around to the left, is heavily wrapped with black electrical tape, and goes into the block as a red wire:



I am very weak where automotive electrics are concerned. Does anyone have any ideas what might be going on here? Because of the current drain, I'm assuming I have a short somewhere. But, as I said, that is a slow drain. As hot as the fuse is getting while running, it seems this could be a different issue? Any advice or opinions would be appreciated, thanks.

Roger
Posted By: John_Kunkel

Re: Need advice on electrical issue - 10/18/14 07:06 PM

It appears that somebody has used the battery terminal on the relay as a constant power source for some accessory...follow the green wire to that accessory.

Mymopar.com has wiring schematics to aid your search.

http://www.mymopar.com/index.php?pid=27
Posted By: RapidRobert

Re: Need advice on electrical issue - 10/18/14 07:09 PM

It ain't stock. It is an added fused power take off from the starter relay battery terminal which is hot all the time. go under the dash & see what is powered on the downstream end of it & post back. we'll see what is being powered but for sure it should be powered instead by a switched 12V source under the dash. In the meantime keep the fuse in your glove box
Posted By: RUNCHARGER

Re: Need advice on electrical issue - 10/18/14 07:10 PM

That's the main power feed to your fusebox. Someone replaced the fuseable link. Put a testlight inline and it will light up. Start pulling fuses until the testlight goes out and your short will be in that circuit. Your amp gauge is also a likely culprit.

Sheldon
Posted By: Fab64

Re: Need advice on electrical issue - 10/18/14 07:19 PM

Thanks for the replies so far.

I forgot to mention that the wire doesn't get hot if it's connected but the engine isn't running - only when running. No wires should be getting that hot while running, should they?

I have the wiring diagram that I found on-line, and am starting to look at it.
Posted By: RapidRobert

Re: Need advice on electrical issue - 10/18/14 07:22 PM

Quote:

That's the main power feed to your fusebox. Someone replaced the fuseable link.

Correct! Sheldon is the man . There is a dead short somewhere inside that blew the FL & they subbed that in to get it up & running & then disconnected it when parked but they did not take care of the dead short. find/fix it. I'm surprised the fuse ain't blowing. EDIT on second thought not a dead short but something is drawing current/on all the time that should not be on
Posted By: dan9

Re: Need advice on electrical issue - 10/18/14 10:02 PM

Something that may help you is to disconnect the negative battery cable and use a test light to connect the cable and the terminal. With everything off and doors closed the light should be out or dim unless it has a newer radio that needs a memory. From what you are saying I'd say the light will be on bright. As you pull fuses the test light will let you know if you found the problem curcuit.
Posted By: Fab64

Re: Need advice on electrical issue - 10/18/14 11:37 PM

Ok, a bit of progress, but mainly more questions. My findings thus far:

1. The fuse which caused the test light to go out is the "Dome & Stop" fuse, left side, second from bottom in the pic below.
2. The Dome & Stop fuse should be 20A, but there is currently a 30A fuse there.
3. I accidentally broke the "Instr & LPS" fuse (top right) getting it out. It is supposed to be 5A, but it was also a 30A fuse.
4. I'm sure Ma Mopar could have made the fuse block more difficult to reach if they'd really tried, but I think they did a pretty darn good job of it as it is.



Oddly, when I connect the main circuit (the one under the hood, which should be a fusible link), neither my dome light nor my brake lights are on unless they are specifically activated by the door switch or by hitting the brakes. Therefore, I'm guessing there must be something else tied into this circuit(?). Back in the old days, my '69 Roadrunner would blow this fuse when someone was sitting in the back seat and I hit the brakes. That was found to be caused by the brake wire sitting between the seat frame and the body, and shorting out when someone sat back there. I will check that first.

I also need to check the amperage of all the other fuses in the block. Since I now know there are at least two which are way stronger than they should be, I'm probably lucky there hasn't been a meltdown of my wiring harness yet. Needless to say, the car will be parked until I can sort this out.

I remain open to suggestions. Thanks!

Roger
Posted By: Supercuda

Re: Need advice on electrical issue - 10/19/14 12:01 AM

Had a Dart that had a drain I could not track down, turns out the trunk light switch needed adjusting after I put new weatherstripping in.

Check the glove box light too.
Posted By: RapidRobert

Re: Need advice on electrical issue - 10/19/14 06:53 AM

Quote:

The fuse which caused the test light to go out is the "Dome & Stop" fuse, left side, second from bottom in the pic below.
2. Oddly, when I connect the main circuit (the one under the hood, which should be a fusible link), neither my dome light nor my brake lights are on unless they are specifically activated by the door switch or by hitting the brakes.

Alright we know the full time errant draw is in the dome/stop circuit or something (improperly) tied into that circuit. Clarify please what you are saying that the dome/brake lights ain't on unless activated by the door/brakes (I know you dont mean that when they (the light(s) themselves) come on when you open the door/hit the brakes) as that is normal operation (I know I am missing something )
Posted By: 72roadrunnergtx

Re: Need advice on electrical issue - 10/19/14 07:57 AM

As mentioned the trunk light, if so equipped, is on that circuit, as well the hazard light flasher. This draw is not the source of heat at the aftermarket fuse holder on the starter relay while running, normal battery charging current is. That fuse holder will not handle that much current without generating some heat. I would start by replacing the fuse holder with the correct sized fusible link. Using a VOM with ammeter function to measure just what your at rest current draw is, would help in identifying the likely cause. The test light method is pretty limited in that regard.

Note; the pictured charge circuit wires/fusible link has been upgraded. The stock fusible link for the ’71 b-body is 16ga.
Posted By: Fab64

Re: Need advice on electrical issue - 10/19/14 08:29 AM

Quote:

Quote:

The fuse which caused the test light to go out is the "Dome & Stop" fuse, left side, second from bottom in the pic below.
2. Oddly, when I connect the main circuit (the one under the hood, which should be a fusible link), neither my dome light nor my brake lights are on unless they are specifically activated by the door switch or by hitting the brakes.

Alright we know the full time errant draw is in the dome/stop circuit or something (improperly) tied into that circuit. Clarify please what you are saying that the dome/brake lights ain't on unless activated by the door/brakes (I know you dont mean that when they (the light(s) themselves) come on when you open the door/hit the brakes) as that is normal operation (I know I am missing something )



What I meant was that if neither the dome or brake lights are on all the time, but are working normally, they can't be the source of the short. But it sounds like there still could be a problem somewhere else on this same circuit, correct? Sorry, as stated earlier, I really don't understand the finer points of electricity.
Posted By: Fab64

Re: Need advice on electrical issue - 10/19/14 08:36 AM

Quote:

As mentioned the trunk light, if so equipped, is on that circuit, as well the hazard light flasher. This draw is not the source of heat at the aftermarket fuse holder on the starter relay while running, normal battery charging current is. That fuse holder will not handle that much current without generating some heat. I would start by replacing the fuse holder with the correct sized fusible link. Using a VOM with ammeter function to measure just what your at rest current draw is, would help in identifying the likely cause. The test light method is pretty limited in that regard.



Ok, thanks. If I have time tomorrow, I will try to measure the at-rest current draw.

Do you happen to know the amp rating of the correct fusible link? Btw, it's not just the fuse that's getting hot; the green wire is also getting very warm. The fuse that's currently in that holder is a 30A, and the wire is 10 gauge.
Posted By: 72roadrunnergtx

Re: Need advice on electrical issue - 10/19/14 08:38 AM

Start with disconnecting the rear body harness in the driver’s side kick panel, see if the draw goes away. Then the hazard light flasher, should be clipped to the steering column support. Other than that, I would be looking for something aftermarket added to that circuit causing the draw.
Posted By: 72roadrunnergtx

Re: Need advice on electrical issue - 10/19/14 08:50 AM

The original charge wire was red and 10ga. pretty common to have issues with resistance and heat build-up at the bulkhead connectors for the circuit, runs from the fusible link to the ammeter. Appears it’s been replaced. Would recommend by-passing the bulkhead connector for that charge wire and the black leg of that circuit running from the ammeter to the alternator output.
Don’t have the amp ratting for the fusible link handy, it is specified out at 16ga. for that application however.


These are 8ga wires BTW.
Posted By: RapidRobert

Re: Need advice on electrical issue - 10/19/14 04:49 PM

Quote:

Do you happen to know the amp rating of the correct fusible link?

iirc the 16 stated is correct for your app also/NAPA sells a 16
Posted By: 72roadrunnergtx

Re: Need advice on electrical issue - 10/19/14 07:08 PM

Posted By: autoxcuda

Re: Need advice on electrical issue - 10/19/14 07:59 PM

Quote:

....


...



What's that red wire coming out of the ACC terminal on the very bottom of your picture go to?

Looking at your other pics, looks like a new engine wiring harness was put on the car at some point.

Not a bad idea to pull the plugs out on the engine side other the fuse box and clean, inspect, tighten female connections. Many times that itself is the draw/resistance on a circuit. But at least for now pull the plug that contains the circuit with that added fuse on it.

You need a very fine blade screwdriver or terminal removal tool. Pop the female connections out from the inside, inspect, clean with wire brush, test how well they grip the male spade connections, and carefully tighten the grip of the female connection with a mini pliers.

Other pics show the has aftermarket tach, 3 aftermarket gauges, MSD, and a separate rev limiter?.

This car was owned by a Moparts member. Forgot his handle.
Posted By: RapidRobert

Re: Need advice on electrical issue - 10/19/14 08:16 PM

HF sells a mini dremel kit for cheap that works perfect for cleaning the fuse holder blades
Posted By: Supercuda

Re: Need advice on electrical issue - 10/19/14 08:23 PM

Quote:



Not a bad idea to pull the plugs out on the engine side other the fuse box and clean, inspect, tighten female connections. Many times that itself is the draw/resistance on a circuit.



Draw? No, extra resistance, yes.

A draw has to have a path to ground. A dirty connection will not have a path to ground, therefore it cannot be a draw. If a connection does have a path to ground (outside it's normal path) then it is a short.

It does not hurt to clean all the connections and put some dielectric grease on the connection to minimize corrosion. Since this is a new to you vehicle that is not 100% stock the FSM can only be a guide. You will have to figure out how the extra stuff is wired in and write it down for future reference.
Posted By: autoxcuda

Re: Need advice on electrical issue - 10/19/14 08:30 PM

Quote:

Quote:



Not a bad idea to pull the plugs out on the engine side other the fuse box and clean, inspect, tighten female connections. Many times that itself is the draw/resistance on a circuit.



Draw? No, extra resistance, yes.

A draw has to have a path to ground. A dirty connection will not have a path to ground, therefore it cannot be a draw. If a connection does have a path to ground (outside it's normal path) then it is a short.

It does not hurt to clean all the connections and put some dielectric grease on the connection to minimize corrosion. Since this is a new to you vehicle that is not 100% stock the FSM can only be a guide. You will have to figure out how the extra stuff is wired in and write it down for future reference.



My bad. Incorrect use of word.

A bad connection will cause extra resistance.
Posted By: Fab64

Re: Need advice on electrical issue - 10/19/14 08:46 PM

Quote:





That red/black wire doesn't appear to be connected to anything. This end is a female plug that's currently empty:



It joins a taped-up group of wires that runs over to the bulkhead connector. I believe the other end is taped up, and unused (you can see it poking out to the left, next to a bunch of other wires). Looks like it previously went into the bulkhead connector box:



I first thought this might be the original fusible-link wire, but the diagram says that wire should be dark blue.
Posted By: 72roadrunnergtx

Re: Need advice on electrical issue - 10/19/14 10:54 PM

Looks like the original charge wire to me, original was Red and ran to cavity #16.
Posted By: Supercuda

Re: Need advice on electrical issue - 10/19/14 11:35 PM

Quote:


My bad. Incorrect use of word.

A bad connection will cause extra resistance.



I figured as much, the OP sounds like he's new to electrical stuff s just wanted to clear up what was what for him. Also for the OP, resistance means heat, so dirty connections will run hot.
Posted By: Fab64

Re: Need advice on electrical issue - 10/20/14 12:58 AM

Quote:

Looks like the original charge wire to me, original was Red and ran to cavity #16.




Well, that's interesting because that's where the green wire (with the inline fuse) is going. Someone else told me this might be the charging wire.

Sorry, I've had other stuff going on, so have not been able to look at this today. I will try to answer the questions posted by others tomorrow. Thanks to all for your suggestions so far.
Posted By: Fab64

Re: Need advice on electrical issue - 10/20/14 02:20 AM

I removed the Dome/Stop fuse, connected the fuse on the green wire and started the car. The green wire and fuse still get very warm - just wanted to confirm to myself that this is a separate issue.

Answers to some questions:

Quote:

Using a VOM with ammeter function to measure just what your at rest current draw is, would help in identifying the likely cause. The test light method is pretty limited in that regard.



I measured the at-rest current draw at 11.89 volts (I simply bridged the green wire at the fuse connection, without the fuse in - is that correct?).

Quote:

What's that red wire coming out of the ACC terminal on the very bottom of your picture go to?



That is being used to supply power to the aftermarket gauges.

Quote:

Looking at your other pics, looks like a new engine wiring harness was put on the car at some point.



How can you tell?
Posted By: autoxcuda

Re: Need advice on electrical issue - 10/20/14 02:29 AM

Quote:

...
Quote:

Looking at your other pics, looks like a new engine wiring harness was put on the car at some point.



How can you tell?



The tag on this loom says M & H. And the wires look clean and fresh. M & H are the ones that make the good quality wiring exclusively for Year One.

M & H is just in Santa Fe Springs, CA. But you can't buy anything Mopar from them direct because they have exclusive sales agreements with Year One on Mopar stuff.

Posted By: 72roadrunnergtx

Re: Need advice on electrical issue - 10/20/14 02:38 AM

"I measured the at-rest current draw at 11.89 volts (I simply bridged the green wire at the fuse connection, without the fuse in - is that correct?)."

Sounds like you are measuring voltage drop, while useful to some extent under some circumstances, not what I was talking about here. Some better VOMs have an ammeter function to measure the actual amount of current draw in amps or milliamps. Can be helpful to identify likely causes to know just how much current draw is taking place. Clearly not a dead short or fuses would be blowing in this scenario.
To be clear, there is two separate problems as I understand your OP, the overheating replacement fuse holder a wire under the hood while running and the apparent current draw on the dome/hazard light circuit if the replacement charge wire is left connected to the starter relay for any length of time at rest.
Posted By: Fab64

Re: Need advice on electrical issue - 10/20/14 03:07 AM

Quote:

"I measured the at-rest current draw at 11.89 volts (I simply bridged the green wire at the fuse connection, without the fuse in - is that correct?)."

Sounds like you are measuring voltage drop, while useful to some extent under some circumstances, not what I was talking about here. Some better VOMs have an ammeter function to measure the actual amount of current draw in amps or milliamps. Can be helpful to identify likely causes to know just how much current draw is taking place. Clearly not a dead short or fuses would be blowing in this scenario.




Here's what I have:



I just tried it again, using both the 200mA DC and the 10A DC settings (on the right side of the dial), and it showed zero on both.

Quote:

To be clear, there is two separate problems as I understand your OP, the overheating replacement fuse holder a wire under the hood while running and the apparent current draw on the dome/hazard light circuit if the replacement charge wire is left connected to the starter relay for any length of time at rest.



Yes, I am convinced these are two separate issues.
Posted By: 72roadrunnergtx

Re: Need advice on electrical issue - 10/20/14 03:17 AM

When set to 10a mode, need to move the red lead over to the other side of the VOM. Would appear in the 200ma mode, leads stay put. Be sure to connect in series with load, as with the test light method or voltage drop. Do you have your dome/hazard light fuse back in place?
Posted By: Fab64

Re: Need advice on electrical issue - 10/20/14 03:24 AM

Quote:

When set to 10a mode, need to move the red lead over to the other side of the VOM. Would appear in the 200ma mode, leads stay put. Be sure to connect in series with load, as with the test light method or voltage drop. Do you have your dome/hazard light fuse back in place?



Good grief, nothing like displaying one's profound ignorance in a public forum, hmm? LOL!! Ok, it measures at 0.96 in that setting.
Posted By: 72roadrunnergtx

Re: Need advice on electrical issue - 10/20/14 03:41 AM

Light bulb somewhere, is there a trunk light? if so equipped, disconnect it from the rear harness in the trunk near the driver's side rear wheel well, single male/female spade connector, single blue wire headed up to the left trunk hinge. try again.

Make sure the trunk lamp is mounted correctly or it won't shut off when closed.
Posted By: Fab64

Re: Need advice on electrical issue - 10/20/14 05:27 AM

Quote:

Light bulb somewhere, is there a trunk light?



No, no trunk light fixture, and no wire for it. I will check the glove box light tomorrow. Thanks again for your help!
Posted By: 72roadrunnergtx

Re: Need advice on electrical issue - 10/20/14 07:03 AM

Glove box light is on a different circuit than the dome/hazard lights. I would still disconnect the rear body harness at the driver’s kick panel to eliminate that leg of the circuit. 960ma is about what a standard sized bulb (#1156) draws. Short of that, maybe something aftermarket added to that circuit.
Posted By: Fab64

Re: Need advice on electrical issue - 10/20/14 07:39 AM

Quote:

Glove box light is on a different circuit than the dome/hazard lights. I would still disconnect the rear body harness at the driver’s kick panel to eliminate that leg of the circuit. 960ma is about what a standard sized bulb (#1156) draws. Short of that, maybe something aftermarket added to that circuit.



Success! I had removed the driver's kick panel earlier today, but I couldn't see any connectors. I just went back out and pulled back a wide piece of black tape, and found at least two connectors hidden behind it. I unplugged this small one which has pink & yellow wires, and the test light went out:



Do you know what this one is for - EDIT: possibly the key-in warning buzzer?
Posted By: 72roadrunnergtx

Re: Need advice on electrical issue - 10/20/14 08:08 AM

Yellow & pink wires? That’s the dome light wiring. Runs up through the driver’s side a-pillar to the dome light. I understood the dome light was working as designed, going out when the door was closed. Check to make sure the correct blub was used, #1004.
Posted By: Fab64

Re: Need advice on electrical issue - 10/20/14 08:18 AM

Good grief, you guys are going to think I'm a moron. I just realized that I've had the driver's door open while I've been doing all my testing. So, of course, the light goes out when I unplug the stop/dome fuse, or disconnect the dome connector.

I just used my test light to check the current in the green wire with the door closed. The light is very dim, just barely lit. The VOM doesn't show anything in the 10A setting, or on the 200mA setting (with the red lead plugged into the correct hole). Sorry for the wild goose chase. I'll pick this up again in the morning (after likely dreaming about it all night ).
Posted By: 72roadrunnergtx

Re: Need advice on electrical issue - 10/20/14 06:11 PM

If the test light is glowing at all, there is some current flowing, however small. Check that the VOM selector is in the 200maDC position. Should be able measure something.
Posted By: Fab64

Re: Need advice on electrical issue - 10/20/14 11:17 PM

Ok, I've found the cause of the current drain (for real this time - LOL!!). It was a red wire that was plugged into the BATT terminal on the fuse block (at bottom left in pic below):



This wire was running to the Sunpro tach that is in the car:



I located a pdf manual on the Sunpro site. The manual says the red wire should be connected to a power source which is on ONLY when the key is in the RUN (not ACC) position. The BATT terminal of the fuse block is always hot, so that was the drain.

Is there a recommended source that you guys use, which is only hot when the ignition key is in the RUN position?

Btw, I checked the rest of the fuses in the block. All were correct 20A except for the two 30A that were in the INSTR & DOME/STOP slots. I will replace those with the correct 5A & 20A.

So, this should resolve my current drain problem, but I still have the issue with the green wire running very hot. A few of you have suggested replacing the fusible link with the correct 16 ga wire. To clarify, are the "charge wire" and "fusible link" the same wire? Will this in itself take care of the heating issue? Btw, I checked the NAPA website and could find no hits on "fusible". Is this a common item? Would the Dodge dealer have it, or is this one of those items that's too old?

It was also suggested that I might want to by-pass the bulkhead connector for the charge wire and the black leg of the circuit running from the ammeter to the alternator output. I will start looking into this.

Thanks for bearing with me through this ordeal. I have actually learned much.
Posted By: 72roadrunnergtx

Re: Need advice on electrical issue - 10/20/14 11:49 PM

Locate the 3-way accessory tap(yellow), should be around the radio on the dash harness. Takes a male bullet connector, a fused key-hot power take-off, use that for the tach.

There are some reproduced fusible links that are terminated with correct connectors for some Mopar applications. Parts stores will have some replacement fusible links with generic connectors or will sell fusible link in small coils without terminals. See pics above on how it is used on that circuit, no more than 4-5 inches in length at the relay stud, straight wire for remainder of the run to the bulkhead connector or by-passing the bulkhead and running straight to the ammeter. Upsizing this wire run would be recommend as well.
Posted By: Supercuda

Re: Need advice on electrical issue - 10/21/14 12:52 AM

NAPA 16 ga fusible link with ring terminal

http://www.napaonline.com/Catalog/Catalo...4695_0452800294

All I did was do a search at napaonline for a fusible link.

http://www.napaonline.com/Catalog/Result...6Dp%3d3%26N%3d0

BTW, good job staying with it. The ACC terminal on the fuse block should only be hot with the key, not always.
Posted By: RapidRobert

Re: Need advice on electrical issue - 10/21/14 07:28 AM

Something blew the OE fusible link and I wouldn't think it would be the constant draw from the tach being being on all the time but if you have no draw now cross your fingers & continue on. NAPA does have the fusible links, I would call em. I would solder it in using heat sink clips to keep the heat away from the rest of it's length as much as you can (solder fast). As you mentioned replace the fuses with the correct ones. The charge wires are the 2 main in/out wires in the bulkhead one of which is the FL wire going from batt/starter relay to FL to/thru bulkhead to the ammeter inside and the other is the large wire going out to the alt. Nacho's parallel bypass is to run those 2 wires straight thru the bulkhead rather than using 2 pairs of connectors in the bulkhead to join them (drill out the 4 bulkhead cavities (2 in each half) & solder in 2 pieces of wire). If the green wire is running hot either it is passing too much current or it is too small or a terminal close to it has high resistance (poor connection) & that friction on the electrons is making heat. I would power the tach from the heater circuit in the fuse box. It is switched 12V and heavy wire as the heater takes alot of juice & tap into the terminal on the back side of the fuse box (the upstream side of that particular fuse) so you tapping in before the circuit hits the fuse & run an inline fuse holder fused line out to the tach. Not sure what amp fuse you need (ask Sun or on here). If the tack does not draw much current then you might be able to tap into a switched 12V source right there on the back side of the dash as mentioned as it'd be closer to the tach (do your homework). EDIT Missed that Supercuda has got ya covered on the FL
Posted By: Fab64

Re: Need advice on electrical issue - 10/21/14 08:27 AM

Quote:

Something blew the OE fusible link and I wouldn't think it would be the constant draw from the tach being being on all the time but if you have no draw now cross your fingers & continue on.



The draw from the tach was so low that I can't believe it would blow the link. My test light was barely glowing orange.

Quote:

Nacho's parallel bypass is to run those 2 wires straight thru the bulkhead rather than using 2 pairs of connectors in the bulkhead to join them (drill out the 4 bulkhead cavities (2 in each half) & solder in 2 pieces of wire).



I assume this is the same modification described by 72roadrunnergtx, above?

Quote:

I would power the tach from the heater circuit in the fuse box.



I've already connected the tach to the 3-way tap above the radio (also described by 72roadrunnergtx, above) - but I will try to find out how much current it draws, and change if need be.

Thanks to all for the info!
Posted By: dan9

Re: Need advice on electrical issue - 10/21/14 03:44 PM

So we can all learn something from this problem. Your pics show the big red wire was connected to the acc terminal on the right side of the fuse box. I was going to suggest you unplug it too but someone else asked about it before me. To my knowledge it should only be hot with the key on. After you said you found the problem you said it was plugged into the left side {batt}. I hope you have found that part of your problem but you may want to check that acc terminal to see if it is hot all the time.
Posted By: 72roadrunnergtx

Re: Need advice on electrical issue - 10/21/14 04:58 PM

The dash harness accessory power tap originates at the fuse panel ACC bus bar via the 20a fuse labeled “ACC”. It is the same location used by the factory to power the optional factory tach, and other “key-on” electrical accessories on this model. Both the heater feed/fuse and the male spade at the bottom of the fuse panel are also powered by this bus, of the various suggestions mentioned here, little difference where the aftermarket tach is powered from other than the fuse panel male spade is unfused. And no, the tach did not “blow” the fusible link. The reason the link was replaced with a fuse holder appears to be unknown to the current owner, no point in speculating now.
The bulkhead connector by-pass described has been taking place since these cars were new and there have been a few variations over the years. The Nacho referral relates to a helpful current Moparts member who regularly contributes here on the electrical issues such as this and has his own slight variation of what has been described. Main point is get the charging current away from the factory spade connectors in the bulkhead connectors.
Posted By: Fab64

Re: Need advice on electrical issue - 10/21/14 05:56 PM

Quote:

So we can all learn something from this problem. Your pics show the big red wire was connected to the acc terminal on the right side of the fuse box. I was going to suggest you unplug it too but someone else asked about it before me. To my knowledge it should only be hot with the key on. After you said you found the problem you said it was plugged into the left side {batt}. I hope you have found that part of your problem but you may want to check that acc terminal to see if it is hot all the time.



Sorry, my bad. Actually, there was a wire in each of these terminals - I didn't post a pic of that. The BATT side, always hot, was powering the tach. The ACC side, hot only with key in ACC position, is still being used to power the aftermarket gauges (oil press, temp, vacuum). If I had a clue as to what I was doing , I would have zeroed in on these wires from the start. Oh, well - lesson learned for next time.
Posted By: Fab64

Re: Need advice on electrical issue - 10/21/14 06:08 PM

Quote:

The dash harness accessory power tap originates at the fuse panel ACC bus bar via the 20a fuse labeled “ACC”. It is the same location used by the factory to power the optional factory tach, and other “key-on” electrical accessories on this model. Both the heater feed/fuse and the male spade at the bottom of the fuse panel are also powered by this bus, of the various suggestions mentioned here, little difference where the aftermarket tach is powered from other than the fuse panel male spade is unfused. And no, the tach did not “blow” the fusible link. The reason the link was replaced with a fuse holder appears to be unknown to the current owner, no point in speculating now.

The bulkhead connector by-pass described has been taking place since these cars were new and there have been a few variations over the years. The Nacho referral relates to a helpful current Moparts member who regularly contributes here on the electrical issues such as this and has his own slight variation of what has been described. Main point is get the charging current away from the factory spade connectors in the bulkhead connectors.



Thanks very much for the clarification on both of these points. I did manage to dig up this post from NachoRT74, which provides a lot of detail on this modification:

Nacho's charging and wiring upgrade

Btw, I have intentionally avoided discussing the PO, or why any of this may have been done. I'm not interested in finger-pointing or assigning blame; I just want to fix these issues and make sure I don't damage anything. I knew the car had a few issues when I bought it. Dealing with all of this stuff is part of the "fun" (Ha!!) of the ownership experience, hmm?
Posted By: dan9

Re: Need advice on electrical issue - 10/21/14 08:11 PM

Well at least you know we are paying attention!
Posted By: Fab64

Re: Need advice on electrical issue - 10/22/14 09:14 PM

Quote:

Well at least you know we are paying attention!



True! Actually, I'm amazed that this post has gotten so much attention - nearly 800 views so far.

Anyway, I'm going to let this post die. I'm compiling a list of questions on the charge/fusible link wiring upgrade, so I'll create a new post just for that issue. Thanks again to everyone for helping me out on this problem - this forum continues to be an invaluable source of info!!
Posted By: RapidRobert

Re: Need advice on electrical issue - 10/22/14 11:30 PM

Quote:

Anyway, I'm going to let this post die. I'm compiling a list of questions on the charge/fusible link wiring upgrade, so I'll create a new post just for that issue.

Whatever you do dont delete it or you will (likely) incur some severe wrath (not from me tho). I'd suggest keeping it going & just adding on addit'l related electrical Q's & it'll all be together.
Posted By: Fab64

Re: Need advice on electrical issue - 10/23/14 07:35 AM

Quote:

Whatever you do dont delete it or you will (likely) incur some severe wrath (not from me tho). I'd suggest keeping it going & just adding on addit'l related electrical Q's & it'll all be together.



Ok, we'll save it as a case study in what NOT to do - LOL!!

My first question concerns re-installing the fusible link: A Powermaster alternator was added by the PO, but I don't know its output. I couldn't find any labeling or printing anywhere on it:





Assuming it's a higher-output alternator, is there any concern in using the standard (Dorman 85627) fusible link? Or is there a higher-capacity fusible link that I should use?
Posted By: RapidRobert

Re: Need advice on electrical issue - 10/23/14 04:01 PM

Quote:

Assuming it's a higher-output alternator, is there any concern in using the standard (Dorman 85627) fusible link?

No you're fine on that & in fact it'd be more likely the other way that the FL would not open soon enough which was the case on my 66 dart as the main in/out charge wires in the eng bay were (the insulation) was melted & the FL was still open which makes me think the PO had a dead short that melted the FL. Best way to understand juice is to compare it to water flow in pipes. Say in a college dorm 10 people are showering at the same time (you're running a killer stereo system) the water psi has to be adequate or some wont get enough pressure. On the car your powermaster alt will supply enough amperage to maintain that amt of flow needed and that will maintain normal charging voltage (pressure) but all that amperage (flow) wreaks havoc on the bulkhead/wires as it ain't designed for that much flow as Ma used the bare minimum needed (she was in it for a profit which is what business is all about) & that is why Nacho's bulkhead parallel bypass is needed and better is to in addition relay add ones directly to the alt which keeps the ammeter honest and the add ons are fed directly from the source (the alt) & keeps all that extra current away from the rest of the system. The Madd bypass is good but you lose the ammeter function
Posted By: 72roadrunnergtx

Re: Need advice on electrical issue - 10/23/14 05:48 PM

Fusible links are sized in relation to the wiring they protect and the expected current load. Unlike a fuse they react slowly to allow for temporary spikes in current close to the max rated current. The battery is the main source of energy capable of lighting up wiring and causing electrical fires. Fusible links are there to protect the larger unfused vehicle wiring from the battery. If you are not planning to increase the size of the charge circuit wiring, and/or increase the total vehicle electrical loads, there will be no need to increase the size of the fusible link. If you planning to by-bass the bulkhead connectors, I would advise you to up the size of the wires to reduce overall resistance in the circuit, especially if that is a high output alternator (75amp or so), stick with the 16ga fusible link.
In your case, warm aftermarket fuse holder & replacement charge wire with the engine running, indicates too high of resistance for the given charging current taking place at the time. A replacement alternator with a higher than stock output rating and a battery that is anything less than at a full state of charge will contribute to heat at any point between the alternator and the battery where there is resistance. Bulkhead connectors in this circuit have been a problem from the beginning. There was a large C-body recall back in the seventies that involved adding a pre-fabricated parallel charge wire between the alternator and the fuse panel bus bar. Same basic design as this.
Posted By: Supercuda

Re: Need advice on electrical issue - 10/23/14 06:11 PM

Quote:

Fusible links are sized in relation to the wiring they protect and the expected current load. Unlike a fuse they are react slowly to allow for temporary spikes in current close to the max rated current. The battery is the main source of energy capable of lighting up wiring and causing electrical fires. Fusible links are there to protect the larger unfused vehicle wiring from the battery. If you are not planning to increase the size of the charge circuit wiring, and/or increase the total vehicle electrical loads, there will be no need to increase the size of the fusible link. If you planning to by-bass the bulkhead connectors, I would advise you to up the size of the wires to reduce overall resistance in the circuit, especially if that is a high output alternator (75amp or so), stick with the 16ga fusible link.
In your case, warm aftermarket fuse holder & replacement charge wire with the engine running, indicates too high of resistance for the given charging current taking place at the time. A replacement alternator with a higher than stock output rating and a battery that is anything less than at a full state of charge will contribute to heat at any point between the alternator and the battery where there is resistance. Bulkhead connectors in this circuit have been a problem from the beginning. There was a large C-body recall back in the seventies that involved adding a pre-fabricated parallel charge wire between the alternator and the fuse panel bus bar. Same basic design as this.



Pretty good write up, but one thing needs to be made clear, it's touched on in the post but I just wanted to specifically point it out. There is no fusible link between the alternator and any load other than the battery. With the engine running, the alternator supplies all the electricity for all the loads. Only the battery has a fusible link, the rest of the loads should be protected by the fuses in the fuse block.

If you add stuff to the system make sure it is fused.
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