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I need a reason why this happenend - Electrical
#891097
12/29/10 11:28 AM
12/29/10 11:28 AM
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Joined: May 2003
Posts: 8,430
St Charles MO
70Coronet500Vert
OP
master
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OP
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Joined: May 2003
Posts: 8,430
St Charles MO
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Can any of you help with an idea of what happened here?
My son has a 1972 Charger, 400, nothing special.
Recently the car would not start, dash was dead, hideaways woould not work. I got under the dash and found the main harness off of the column, the start harness, had melted. The red wire from the Batt was the main melted component.
We recently replaced the voltage regulator with a new unit and the car quit working two days later. But, that should not affect this particular wire should it? Also, we have an aftermarket stereo with about 1400 W, but again, that should not affect this wire.
I broke the melted harness apart and cleaned up the terminal, put it back together and car starts, runs and drives fine.
But why.what caused that particular wire to overheat? I am thinking only a short could have caused that much current flow. Also, the conttacts were clean, no dirt present.
No matter how responsible he may seem, never give your gun to a monkey!
1970 Coronet Vert
1972 Charger
1974 Satellite Sebring Plus Sundance
2001 Ram 4x4
2002 Intrepid
2006 300C
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Re: I need a reason why this happenend - Electrical
[Re: 70Coronet500Vert]
#891099
12/29/10 11:52 AM
12/29/10 11:52 AM
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Joined: Mar 2007
Posts: 3,285
West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,285
West Coast, USA
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The response above covers it. You can also read up on the bulkhead connector and other issues here.... http://www.madelectrical.com/electricaltech/amp-gauges.shtml
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: I need a reason why this happenend - Electrical
[Re: jbc426]
#891100
12/29/10 12:01 PM
12/29/10 12:01 PM
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Joined: Oct 2007
Posts: 288
Birmingham, England
Mick70RR
enthusiast
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enthusiast
Joined: Oct 2007
Posts: 288
Birmingham, England
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That happened to me a few weeks ago. I cut the red and black wires out of the connector and re-connected them separately. Luckily these two wires are looped either side of the connector, almost like the engineers knew what was going to happen.
1970 Road Runner
505 cid
MCH CNC ported Stealth heads
MP 528 camshaft
4 speed
GV overdrive
11.98 @ 117 on street treads
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Re: I need a reason why this happenend - Electrical
[Re: Mick70RR]
#891102
12/29/10 01:11 PM
12/29/10 01:11 PM
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Joined: Sep 2007
Posts: 14,889
up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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All the switched 12V current goes thru this connection. If you put a 1400W stereo in and the current for it is going thru this connection then you have found your problem.
Fix it and add a high current relay to feed the stereo, used the ignition switch 12V to trigger the relay.
1400W is like 100A just for the stereo alone.
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.
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Re: I need a reason why this happenend - Electrical
[Re: 70Coronet500Vert]
#891103
12/29/10 01:36 PM
12/29/10 01:36 PM
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Joined: Oct 2010
Posts: 606
Montana
Yancy Derringer
mopar
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mopar
Joined: Oct 2010
Posts: 606
Montana
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Quote:
stereo with about 1400 W, but again, that should not affect this wire.
only a short could have caused that much current flow.
I'd like to see how you connected that 1400w stereo
A 1400W stereo IS a short circuit
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Re: I need a reason why this happenend - Electrical
[Re: CRE2004]
#891104
12/29/10 01:59 PM
12/29/10 01:59 PM
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Joined: Mar 2007
Posts: 3,285
West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,285
West Coast, USA
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There's really no need for the "Upgraded" wiring you seek. A properly designed system would not pass more current through the bulkhead connector. Any exsisting or additional high power electrical loads would be fed from a distribution lug, typically located in the engine compartment, where the "upgraded" alternator connects to distibute the higher current demanded by power hungry accesories. The electrical load at the bulkhead would be reduced, as only switched power and some lighting voltage would flow through the connectors. All heavy electrical loads would then be handled by relays fed from the distribution lug/ lugs on the same side of the firewall as where it is produced. Also, one wire alternators have shortcomings. The most notable is the lack of a remote voltage sensing feature. All this information is discused in further detail on MadElectric's website. http://www.madelectrical.com/electrical-tech.shtmlAfter going through all this information recently, as a result of needing to learn how to effectively add significant electrical loads to my 1970 e-body; I ended up with a "2-layered" electrical system if you will. All my additional electrical loads, fuel pump, electric fans, MSD ignition, A/C, and power windows are fed from a main distribution panel in the engine compartment using relays. The control power for the relays is triggered by low-current switched voltage that passes through the bulkhead. Essencially, the power for the exsisting dash, tail/brake lights, side marker, interior and parking lights etc are now treated as just another circuit that is fed off the upgraded distribution system under the hood THROUGH THE ORIGINAL BULKHEAD WIRES, which now have a reduced load to carry. All high power consumption items have been swapped to the front distribution circuit. Here's a pic of the fused distribution panel during installation. The dash etc wiring I mentioned still goes through the original type fusible link through the bulkhead, but now carries a lot less current. The weakest link in this chain is then the Mopar or Denso type alternators. They produce too low of an amperage at idle. The solution I chose was the late model Delco-Remy CS 144, which puts out over 115 amps at idle and much more at speed. They come in late model Escalades, Yukons etc.
Last edited by jbc426; 12/29/10 02:25 PM.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: I need a reason why this happenend - Electrical
[Re: 70Coronet500Vert]
#891105
12/29/10 04:01 PM
12/29/10 04:01 PM
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Joined: Jan 2003
Posts: 28,068
Irving, TX
feets
Senior Management
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Senior Management
Joined: Jan 2003
Posts: 28,068
Irving, TX
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He needs to get the amp off the factory wiring harness. It wouldn't hurt to pull the stereo off the wiring too. That goes for anything electrical added to the car. Run a power lead from the battery, starter relay lug, or alternator output lug to a distribution block. Something like this works great:  They've got bigger fused units too:  I've got a couple of these 75 amp relays to handle switching power for things the little ice cube relays can't handle:  If you need anything stronger than that, use a Ford starter relay. 
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
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Re: I need a reason why this happenend - Electrical
[Re: jbc426]
#891106
12/29/10 04:53 PM
12/29/10 04:53 PM
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Joined: Oct 2010
Posts: 606
Montana
Yancy Derringer
mopar
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mopar
Joined: Oct 2010
Posts: 606
Montana
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Quote:
There's really no need for the "Upgraded" wiring you seek. A properly designed system would not pass more current through the bulkhead connector.
This is just not quite true
Unless he's modified the charging circuit to eliminate the bulkhead connector, and upgraded the loads in the car, EVEN STOCK LOADS are pushin' it for a stock bulkhead connector. I had trouble with my '70 RR LONG before there was such a thing as 1400w stereos.
I agree with the theme of your ideas, however. In my old Landcruiser, NOTHING ran off the ignition switch except the coil of a "continuous duty" solenoid. all switched loads went through that nice be relay.
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Re: I need a reason why this happenend - Electrical
[Re: Yancy Derringer]
#891107
12/29/10 05:45 PM
12/29/10 05:45 PM
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Joined: Mar 2007
Posts: 3,285
West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,285
West Coast, USA
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Quote:
Quote:
There's really no need for the "Upgraded" wiring you seek. A properly designed system would not pass more current through the bulkhead connector.
This is just not quite true
Unless he's modified the charging circuit to eliminate the bulkhead connector, and upgraded the loads in the car, EVEN STOCK LOADS are pushin' it for a stock bulkhead connector. I had trouble with my '70 RR LONG before there was such a thing as 1400w stereos.
I agree with the theme of your ideas, however. In my old Landcruiser, NOTHING ran off the ignition switch except the coil of a "continuous duty" solenoid. all switched loads went through that nice be relay.
Let me clarify. My charging circuit goes to a distribution block in under my hood. Battery gets charged from there. Amp gauge is bypassed. The instruments, interior lighting, side markers, turn signals, tail lights, brake lights, parking lights and factory AM 8track are the only thing fed by what used to be the main charging circuit wires. I think the bulkhead connections are fine with that type of load.
Last edited by jbc426; 12/29/10 05:47 PM.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: I need a reason why this happenend - Electrical
[Re: feets]
#891108
12/30/10 07:50 AM
12/30/10 07:50 AM
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Joined: Mar 2010
Posts: 357
Lake Elmo, MN
Evil Monkey
enthusiast
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enthusiast
Joined: Mar 2010
Posts: 357
Lake Elmo, MN
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Quote:
Run a power lead from the battery, starter relay lug, or alternator output lug to a distribution block.
There's a huge difference between pulling the power for a distribution block from the battery/starter relay lug and from the alternator output lug. You want to make sure to pull the power from the alternator output lug, for this reason:
If you pull from the alternator output lug, you are getting the power directly from the source (the alternator), without anything else in between, and the power to the distribution block all stays under the hood.
If you pull the power from the battery or from the starter relay lug, the power comes from its source (the alternator), then has to go through the bulkhead connector to the interior, through the ammeter, back through the bulkhead connector and into the underhood area (where it started from anyway), and then finally to the point you are drawing the power from (the battery or starter relay lug).
Drawing power for a distribution block that powers a large amplifier (or any other high powered devices) from your battery or starter relay lug puts a huge amount of current through the bulkhead connector and ammeter, which could fry either one, unless you have made other electrical system modifications, like bypassing the bulkhead connector and ammeter by running a large gauge wire from the alternator output lug to the battery or starter relay lug. Mopars in the latter half of the 70s, like the '78 Aspen I owned, had a wire running directly from the alternator to the battery from the factory, and you could connect high power accessories or distribution blocks directly to the battery without issues. Earlier cars (like my 74 Cuda) do not have that direct connection between the alternator and battery, and should have high powered accessories or distribution blocks connected to the alternator side of the electrical system, before the power goes through the bulkhead connector.
1974 'Cuda 360/TKO
1990 Ram Van
1998 Neon
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Re: I need a reason why this happenend - Electrical
[Re: Evil Monkey]
#891109
12/30/10 10:55 AM
12/30/10 10:55 AM
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Joined: Mar 2007
Posts: 3,285
West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,285
West Coast, USA
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Quote:
Quote:
Run a power lead from the battery, starter relay lug, or alternator output lug to a distribution block.
There's a huge difference between pulling the power for a distribution block from the battery/starter relay lug and from the alternator output lug. You want to make sure to pull the power from the alternator output lug, for this reason:
If you pull from the alternator output lug, you are getting the power directly from the source (the alternator), without anything else in between, and the power to the distribution block all stays under the hood.
If you pull the power from the battery or from the starter relay lug, the power comes from its source (the alternator), then has to go through the bulkhead connector to the interior, through the ammeter, back through the bulkhead connector and into the underhood area (where it started from anyway), and then finally to the point you are drawing the power from (the battery or starter relay lug).
Drawing power for a distribution block that powers a large amplifier (or any other high powered devices) from your battery or starter relay lug puts a huge amount of current through the bulkhead connector and ammeter, which could fry either one, unless you have made other electrical system modifications, like bypassing the bulkhead connector and ammeter by running a large gauge wire from the alternator output lug to the battery or starter relay lug. Mopars in the latter half of the 70s, like the '78 Aspen I owned, had a wire running directly from the alternator to the battery from the factory, and you could connect high power accessories or distribution blocks directly to the battery without issues. Earlier cars (like my 74 Cuda) do not have that direct connection between the alternator and battery, and should have high powered accessories or distribution blocks connected to the alternator side of the electrical system, before the power goes through the bulkhead connector.
Absolutely correct! But, I'm pretty sure he meant to run power from those sources once the other modifications are done such as running the fused alternator cable straight to the starter relay lug or distribution lug, bypassing the amp guage and bypassing the bulkhead connector.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: I need a reason why this happenend - Electrical
[Re: jbc426]
#891110
12/30/10 11:23 AM
12/30/10 11:23 AM
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Joined: Jan 2003
Posts: 5,444
Indiana
YO7_A66
master
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master
Joined: Jan 2003
Posts: 5,444
Indiana
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"fused alternator cable"
What size fuse should be applied to the wire that goes from the alt to the relay?
Thanks
1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
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Re: I need a reason why this happenend - Electrical
[Re: YO7_A66]
#891111
12/30/10 11:27 AM
12/30/10 11:27 AM
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Joined: Sep 2007
Posts: 14,889
up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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Depends on the laod and the size of the wire. You want your fuse to be rated at less than the maximum carrying capacity of the wire. However, if your load was, for example, 50A and you wire could carry 75A safely I would probably go with a fuse between those two numbers, say 60A or so. A ten percent overage in fuse versus load numbers is about right.
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.
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Re: I need a reason why this happenend - Electrical
[Re: YO7_A66]
#891112
12/30/10 11:30 AM
12/30/10 11:30 AM
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Joined: Mar 2007
Posts: 3,285
West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,285
West Coast, USA
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It depends on the elecrical load the wire/cable can carry. I am running 5 feet of #2 cable with a 200 amp fuse, but then again my alternator can put out over 170 amps and a #2 cable can handle that at 5 feet of length.
An alternator will only produce what is required up to it's rated capacity. I wanted relatively high output at idle speeds etc and my current draw is less than the max output it's capable of.
Determine the amount of amps your alternator produces, measure the length of the cable/wire you need, check the charts for rated amperage carrying capacity versus cable diameter and length, add a safety margin and select a fuse, fusible link or circuit breaker of suitable size to protect the cable/wire.
Here's a tip, Marine Supply shops have some cool new styles of heavy-duty, high-amperage DC fusing products worth taking a look at.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: I need a reason why this happenend - Electrical
[Re: jbc426]
#891113
12/30/10 02:08 PM
12/30/10 02:08 PM
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Joined: Jan 2003
Posts: 28,068
Irving, TX
feets
Senior Management
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Senior Management
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Posts: 28,068
Irving, TX
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I ran a large lead from the 140 amp alternator to the battery via the starter relay lug. It's got a 125 amp fuse in it.
With all my goodies on I should never exceed 110 amps. If the draw is larger than that I've got a problem. I carry extra fuses in the car.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
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Re: I need a reason why this happenend - Electrical
[Re: feets]
#891114
12/31/10 10:35 AM
12/31/10 10:35 AM
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Joined: May 2003
Posts: 8,430
St Charles MO
70Coronet500Vert
OP
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OP
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Joined: May 2003
Posts: 8,430
St Charles MO
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Thanks guys. I need to look at the wiring diagram again. I have taken a #2AWG to the rear of the car to a power distribution block and feed 2 Audiobahn amplifiers in the trunk. I know it is a bit undersized, but it is what it is for now.
This main stereo wire is connected directly to the battery. But what you all are saying is that this current still passes through the bulkhead and ignition siwtch circuit?
Seems to me this sould be a parallel feed not a series feed and should not be on the bulkhead circuit at all.
No matter how responsible he may seem, never give your gun to a monkey!
1970 Coronet Vert
1972 Charger
1974 Satellite Sebring Plus Sundance
2001 Ram 4x4
2002 Intrepid
2006 300C
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Re: I need a reason why this happenend - Electrical
[Re: 70Coronet500Vert]
#891115
12/31/10 10:42 AM
12/31/10 10:42 AM
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Joined: Mar 2007
Posts: 3,285
West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,285
West Coast, USA
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Quote:
Thanks guys. I need to look at the wiring diagram again. I have taken a #2AWG to the rear of the car to a power distribution block and feed 2 Audiobahn amplifiers in the trunk. I know it is a bit undersized, but it is what it is for now.
This main stereo wire is connected directly to the battery. But what you all are saying is that this current still passes through the bulkhead and ignition siwtch circuit?
Seems to me this sould be a parallel feed not a series feed and should not be on the bulkhead circuit at all.
That sounds normal. Typically, amps have a direct "always on" large gauge battery feed while the control voltage for the power on/off relays inside them goes through the bulkhead via a switched power source.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: I need a reason why this happenend - Electrical
[Re: jbc426]
#891116
12/31/10 10:57 AM
12/31/10 10:57 AM
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Joined: May 2003
Posts: 8,430
St Charles MO
70Coronet500Vert
OP
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OP
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Joined: May 2003
Posts: 8,430
St Charles MO
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Yes, I have a 16AWG amp turn on lead, then the large power lead. This current should not be flowing through the main circuit, but in a way I guess it is. The alternator has to make up this current draw doesn't it? That puts the amp demand back onto the bulkhead circuit.
I need to make an as-built wiring diagram of my car. I am about one more wiring problem away from making new harnesses like I did for my Coronet.
No matter how responsible he may seem, never give your gun to a monkey!
1970 Coronet Vert
1972 Charger
1974 Satellite Sebring Plus Sundance
2001 Ram 4x4
2002 Intrepid
2006 300C
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