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headlight wires smoking and melting

transam

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Hi, Just installed a new Mopar mini high torques starter and installed a new starter solinoid. Nothing happens except some clicks at the solinoid switch. Battery is at 100% and at 14 volts. While standing in front of the battery side fender I all of a sudden smelled wire burning and pulled both battery cables. Pulled the headlight wires off that side and the first 3 iinches from the plug, the insulation was melted and the wires bare? Both headlights and the side marker light on that side? I had already cleaned all the connections and checked the battry to engine and battery to frame grouns which both looked good. Any ideas why this would happen and the best way to diagnose?
 

Challenger RTA

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Might be the alternator shorted out. starter bad or positive contacting motor. That's comes to mind first. I think there is an offset starter connector to prevent that. As far as the headlight wires it could of been the only path to ground. If the headlights were on?

Pictures might help. headlight connectors foot switch, bulkhead connectors, alternator connector.
Best thing to do is undo what you did.
 
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Challenger RTA

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1:RED wire 16 Battery power yellow dot to splice one feeds fuse block, 2:charge wire 18 black wire blue dots to splice one through amp meter to red wire blue dot 16 to battery, 3:ACC feed from splice 1 Red wire Q3_12R yellow dot to steering column. Black wire 12BK red dot to ACC side of fuse box.
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Pay no attention to the 2 headlight wiring.It's the same for 4 headlights
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Ricks72Chlgr440

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Hi, Just installed a new Mopar mini high torques starter and installed a new starter solinoid. Nothing happens except some clicks at the solinoid switch. Battery is at 100% and at 14 volts. While standing in front of the battery side fender I all of a sudden smelled wire burning and pulled both battery cables. Pulled the headlight wires off that side and the first 3 iinches from the plug, the insulation was melted and the wires bare? Both headlights and the side marker light on that side? I had already cleaned all the connections and checked the battry to engine and battery to frame grouns which both looked good. Any ideas why this would happen and the best way to diagnose?
Proper grounding is really important. My son has a truck that was not properly grounded and the system found ground through his B&M shifter cable (which melted it)!
 

Challenger RTA

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This is from an other post if it's your problem.

1701952980156.png
 

transam

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Proper grounding is really important. My son has a truck that was not properly grounded and the system found ground through his B&M shifter cable (which melted it)!
I am searching for my power probe now. But I failed to mention I had replaced my ignition key cylinder a couple weeks ago and the car started fine after install. This car has been garaged and not run much in the past 7 years. All I did was change the starter to a Mopar high torque mini starter and car would not start doing that. So I changed the solinoid switch and all of a sudden those wires melted within seconds and filled garage with smoke. The only other things I have worked on is I removed the tail lights so that harness of bulbs is just lying in the trunk? I don't really think that should effect any of this? I will now have to order a new forward light harness, but I will be afraid to use it. Maybe tape up the melted one and use it to test with?
 

Challenger RTA

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To start You might already have a plan.
I would remove battery and leave light harness connected. Then check all wires to ground and may be to each other. Some circuits may have a completed circuit to ground when on. Some wires may be melted to each other. Doing this might help narrow down just what happened. also open harness may revile what happened.
Unplug from bulkhead test again and compare results. The point being so you don't fry a new harness.
Check fusible link did it blow?
 

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It could be from the bulkhead inward. Leaving the rear harness disconnected would help. Check circuits from bulkhead connector with every thing off. door shut too. You might get a reading when reading the gauge cluster,oil,temp,clock and tach might read ti ground.Depending on you probe.
I would also check each bulkhead wire to each any every wire for a dead short.
The concern here would be The event the alternator shorted out. that the battery and alternator wires heated everything up and meted other wires together. And yes the alt and battery wire should have continuity. If there are any that you get a reading to ground or to each other. Make a note of it. Someone hear can help you out when in dough.
 

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The next thing to do would be to repeat with the ignition switch on. Remember the connector under the column can be unplugged to test from also.
 

transam

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The next thing to do would be to repeat with the ignition switch on. Remember the connector under the column can be unplugged to test from also.
So far I have had my 7 years old optima battery load tested and it dropped to 11 volts and it was at 100% charged. I am going to replace it for starters. I also think I may have an issue with the mini starter studs touching my block which has a nice ground wire coming off the negative side at the battery which also has a nice ground wire going right to the radiator support right next to the battery. This happened so quick as far as smoke and melting, I think if that starter stud touches the block it will feed power right through the block to that negative battery side and also to the radiator support and that is the side the headlight wires cooked on? I am going to remove the mini starter and install the terminal relocation kit and then go from there. But I think it is where I failed.
 

transam

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So far I have had my 7 years old optima battery load tested and it dropped to 11 volts and it was at 100% charged. I am going to replace it for starters. I also think I may have an issue with the mini starter studs touching my block which has a nice ground wire coming off the negative side at the battery which also has a nice ground wire going right to the radiator support right next to the battery. This happened so quick as far as smoke and melting, I think if that starter stud touches the block it will feed power right through the block to that negative battery side and also to the radiator support and that is the side the headlight wires cooked on? I am going to remove the mini starter and install the terminal relocation kit and then go from there. But I think it is where I failed.
Ya, me too. I think I had the key in the on position and as soon as I saw smoke and selled wire I shut the key off and it all stopped. Those starter terminals are very close to the block. I put one in my demon and I used that terminal stud relocation kit. I should have known better and I had another kit right in my garage and did not think it would be needed as this car has no header tubes. But I will find out soon. Meed to now order a new front light harness.
 

pschlosser

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I've had experiences wear one short causes another. This happens when the first wire heats up inside a wire harness and melts the insulation of adjacent wires causing additional shorts. More than once, have I found myself scratching my head why I have a short on something I have not activated or used. Only to discover later, the cause of the secondary shorts was a prior primary one. In some cases, the primary short can be several feet away from the secondary damage.

If the wires are cooked in your headlights, but you weren't using them at the time, then you may have more than one short to contend with.

I once made repairs to a car, tested the repair, and then the car sat for a few weeks before I came back and worked a second repair. During the second repair, I discovered a short. Later, after everything is sorted out and repaired, I see the short started with my first repair wherein the car only ran for 30 seconds before I shut it off. Long enough to melt insulation and cause secondary shorts, but not long enough to smell anything burning.

Best thing to do is undo what you did.

@Challenger RTA nails it.

I recommend you begin by rewinding history. When was the car working in a way without any shorts what so ever? Then, what has changed or repaired since that time?

You may need to go back and recheck those repairs for faults causing shorts. If you're lucky, only one engine compartment wire harness is impacted.

Once resolved, and you're ready to hide the damage, with some effort you can repair the harnesses yourself with any color wire, and hide the wrong colors when wrapping the harness back up in vinyl tape. You will want to keep as much of the correct color wiring that still shows at the ends of the harnesses.

Alternately, you can buy reproduction wiring harnesses and replace those damaged. But, you will want to ensure the cause of the short(s) is resolved before risking a new harness.

Shorts and wiring problems can be a real PITA because they can be hidden and hard to locate. Once a harness is damaged with melted insulation, don't be afraid to unwrap the whole harness to expose any secondary shorts. Fix things first, make it look pretty, later.

If you don't have a soldering iron, go treat yourself to some decent tools. If you don't know how to solder, it's easy to learn by watching some youtube videos. For this kind of work, I would used a nice Weller soldering iron, assorted shrink tubing and a decent heat gun. I mention this last point, because I recommend your repairs all be soldered. Twisting copper together and covering with sticky electrical tape is fine while troubleshooting. But I recommend your final repairs be soldered connections and covered with shrink tubing.
 

72RoadRunnerGTX

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My bet is on a bad negative battery cable, high resistance in one of the ends/terminations. Do a voltage drop test between the engine block and the negative battery post while attempting to crank. Leave the ignition switch off, jump the starter relay for testing. Nothing in the forward lighting harness related to key-on with any kind of current potential that could burn wires. Has to be the lighting ground wires in the harness trying to provide a return path from the starter to the battery. Too, get some jumper cables and jump the negative battery post to the engine block as a test.
 
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