Under dash electrical fire

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68gtxman

68gtxman

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I had an electrical fire in the dashboard harness in May. I was lucky enough to get the positive battery cable off before the car burned up. (Lesson to all of you who wrench on the battery terminals - keep the positive one loose enough to remove by hand.) I saw the wire harness arc over to the dash frame were the metal strap holds part of it in place. The strap must have rubbed a hole in the insulation of the power wire to the amp gauge. There was no fusible link to protect it. I removed the harness a couple of days after this occurred and then I put it in the dishwasher (sans turn signal flasher) to clean it up. I did not know how I would go about repairing the harness, as I didn’t want to buy a bunch of different colored wires and I did not know what gauge they were (now I know that nearly all of them were 16 gauge). I ripped open the fused/melted portions of the harness and yanked each wire free of the melted mess. I watched utube videos of splicing wires in a car and noted that one mechanic dissuaded the use of solder in a splice. He highly recommended a splice crimp be used, and said the double crimp style was excellent for this (see photo below of sample connector and crimped tool). Cover the splices with heat shrink. The fourth photo above is the repaired harness, before I wrap it with the plain plastic tape like the factory did. I tested, cleaned and repaired all the gauges when I had it out. I deleted all the wires that went to the amp gauge and I will add a volt meter to the car later. The third photo shows all the removed wire sections.

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Mike69cuda said:
Buy a new M&H one from Year One. They have sales pretty regularly.
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Yeah its probably well worth it to take a week... pull the seats, the column and put in all new wiring. Even if it is a major pain

Glad your car didn't get hurt - that's a nice ride!
 
68gtxman said:
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I had an electrical fire in the dashboard harness in May. I was lucky enough to get the positive battery cable off before the car burned up. (Lesson to all of you who wrench on the battery terminals - keep the positive one loose enough to remove by hand.) I saw the wire harness arc over to the dash frame were the metal strap holds part of it in place. The strap must have rubbed a hole in the insulation of the power wire to the amp gauge. There was no fusible link to protect it. I removed the harness a couple of days after this occurred and then I put it in the dishwasher (sans turn signal flasher) to clean it up. I did not know how I would go about repairing the harness, as I didn’t want to buy a bunch of different colored wires and I did not know what gauge they were (now I know that nearly all of them were 16 gauge). I ripped open the fused/melted portions of the harness and yanked each wire free of the melted mess. I watched utube videos of splicing wires in a car and noted that one mechanic dissuaded the use of solder in a splice. He highly recommended a splice crimp be used, and said the double crimp style was excellent for this (see photo below of sample connector and crimped tool). Cover the splices with heat shrink. The fourth photo above is the repaired harness, before I wrap it with the plain plastic tape like the factory did. I tested, cleaned and repaired all the gauges when I had it out. I deleted all the wires that went to the amp gauge and I will add a volt meter to the car later. The third photo shows all the removed wire sections.

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Where did you get that tool Please John
 
!!WOW!! My condolences but at same time, sounds like you were LUCKY!!
 
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Here is the repaired harness. I installed it yesterday, but before I start the engine again, I will add a fusible link and track down a few incomplete circuits. Things like the gas/temperature gauges, cigarette lighter and dome lights have never worked, so I’m trying to get them working now.
 
One thing you can do on initial power up is to put a large wattage lamp in series with battery ground, such as stop/ tail lamp, or head light. Some things will work, lights will be dim, but the series lamp will protect the harness against any short
 
Update: I finish reinstalling the repaired harness and added a 60A breaker at the firewall feed. I ran the car for about an hour and it smelled like someone was cooking something somewhere. No smoke thank goodness! I felt the repaired harness and it was cool as a cucumber. Checked the battery and it was what was cooking (it’s in the trunk). The alternator was very hot and so was the MSD controller. I let the battery cool down for about a half hour and it is still fizzing and hot. But it reads 12.5 volts and the load tester showed the battery to be very strong.

I am going to let everything cool down over night (with the battery terminal disconnected) before I start other trouble shooting. My first theory is the electrical fire must have done something to the alternator or the voltage regulator and one or the other must be putting out too high voltage for the system. This should be an easy thing to test, with the engine running for a few minutes.

Has anyone else found something like this before?
 
Oh, the good news is now I have working gas and temperature gauges and a speedometer (need new drive gear to correct for the 4.10 gears). I eliminated the amp gauge, but didn’t install a voltage gauge yet. No more guessing if I have any fuel left in the tank!!!
 
jos51700 said:
Wait.... You ran the HARNESS in the dishwasher?
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Yes, but it had three months to dry out. It was completely dry when I ripped it all apart. I did not put the headlight or ignition switches in with it (nor the gauge cluster).
 
I'm going to say that if you did wash that in the dishwasher, that's probably a bad thing long term. That moisture wicks into every cracked insulator and up inside every wire termination point and will likely lead to long term corrosion issues....

Once that moisture gets in there, it AIN'T coming out.
 
After replacing the voltage regulator, the voltage still hits 18 when revved. No one around here can test alternators not in a running car, so I ordered two (one spare) to replace the one I have. We’ll see as soon as one of them gets here.
 
Sounds like you have a wiring issue that is applying full voltage to the alternator field circuit.
 
I got both rebuilt alternators. Both were DOA!!! The first one put out nothing and the second one would not even spin! I found two old double pulley alternators in the basement and the first one I tried worked normally. What a PITA expecting the rebuilt alternators to work right out of the box. At least I now know that my repaired wiring harness is correct.
 
Yeah!!! I got the newly rebuilt alternator and it works!!! I spent the day cleaning and prepping the car for this Saturday’s car show. We will put the ‘65 and ‘67 convertible in the show this year.
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68gtxman said:
I got both rebuilt alternators. Both were DOA!!! The first one put out nothing and the second one would not even spin! I found two old double pulley alternators in the basement and the first one I tried worked normally. What a PITA expecting the rebuilt alternators to work right out of the box. At least I now know that my repaired wiring harness is correct.
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From 74 to around 85ish I sold parts in two stores. Rebuilts were always "iffy" and it seems like they are way way worse, nowadays
 
That's a nice lookin little car. I sure am glad it didn't get hurt.
 
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