Burnt Ignition Resistor Wire
 

A disaster just sidelined my ’78 7 miles after I solved the steering wheel and gear issue; now I’m forced to ask for help from you electrical forensic experts, and I’ll be thorough:

Last summer I had issues with my courtesy lamps and clock, which are on the same fuse, because one of my wires was pinched between the steering wheel and its mounting bracket, shorting out the fuse; eventually I found the problem and fixed it, along with installing my new quartz movement clock…all was well for several months, until I finally decided to start the steering gear project. After completing that job, I went for a drive:

First I had to charge the battery because it had been in use off and on for a couple of weeks, and the car wouldn’t start; however, after charging the battery I was able to start the car and test drive my alignment…all was right then except for a little off-center turn signal cam, meaning steering adjustments still need to be made; however, after 7 miles with no issues, I parked in a clinic and came out a few minutes later to a struggling starter, and then began to notice burnt plastic smoke coming from my vents. I turned the ignition off, and removed the access panel for that spot – to my dismay, fire was already trying to burn up my car! Fortunately I was able to blow out the fire before it really messed up the car, but unfortunately many wires are either burnt or melted – has anyone experienced such a problem? I’ve posted pics and did some general research – it seems problem wire was the brown and white resistance wire to the ignition switch, but why did it just now fail so badly? I’ve seen suggestions that the alternator could have done it, but it’s less than a year old and seemed to be working perfectly, although I did just notice the alternator post is loose and wiggles a bit; I also replaced the starter 3 months ago to address intermittent slow cranking, but the new starter wasn’t much better, so I upgraded the battery cables to 2 gauge, which didn’t help either. The wires on the engine compartment side appear undamaged.

So, 1) Is the burnt wire the ignition switch resistor, and if so can a replacement be sourced; 2) If I have to make one myself, what are the resistor specs (the length of the wire and the coil should be a certain ohm rating); 3) The wire is stainless steel and can’t be soldered, so how does one efficiently connect a new wire to the connectors at each end; 4) Causation – alternator vs starter…I’m virtually certain no wires were damaged before the problem occurred as I checked them all last summer when I resolved my courtesy lamp circuit short; 5) Whether or not the starter caused the problem, any recommendations on a quality mini starter for a Pontiac 455 with headers; 6) and finally, how much of the wiring must be reinstalled to get my windows down?

I have so much experience with this car, but new mysteries keep happening…thanks for any help!

A 1978 should not have a resistor wire for the ignition. That was only used in "points" ignition cars.

Don't like the alt post wiggling.

Hard to tell looking at pics, but the brown wire on the firewall connector looks like it should possibly go to the headlight switch. There appears to be 2 on that position? The other may go to the turn signal connector or to the IP area?


I'd say one or more made ground and melted. Probably taking some others that were close to that circuit or vicinity?


:confused:

Actually looking again, it appears (brown wire) to be the one that goes to the alternator.
Probably something broke in there?


:confused:

I located two brown and white wires in my service manual, with one going to the headlight switch and the other from the bulkhead connector to the ignition switch connector, through the resistor shown in the photo; the brown wire to the headlight switch is fine and actually goes through the fuse block, which would have prevented this wire burning...GM really stepped on their johnson's by not fuse-protecting this ignition circuit! I also am confused by the comments I've seen about the resistor not being needed in HEI vehicles, but that's the way my car came from the factory, as I've had it since then! Is it possible I can just put things back together and just delete the resistor wire? I don't have any fancy aftermarket ignition components installed, all stock...

...and no possibility of a worn wire, as I went through that drill last summer and checked all of my wires and was meticulously careful when I put everything back together...

The Cause?
 

That resistor wire should never have seen enough current to have a melt down.

It's the excite wire to terminal 0ne in the voltage regulator.

Get the alternator checked out and inspect the wires going to it that run along the intake.

Look close where the brown wire runs beside the master splice for the fusible link wires.

Need to find the cause before repairs under the dash.

Clay

If the alt bolt is loose and finds an internal ground, you will melt wires and fusible links.

George

The possible culprit? I see the loose alternator post has the plastic bushing burnt, but the wires from the bulkhead to the alternator appear undamaged. It was putting out 14 volts when I was driving...perhaps under the load of trying to start it shorted internally? It's still hard to understand how only the exciter burnt up between the ignition switch and the bulkhead...

Assuming the alternator caused all this, how should I replace the exciter wire? It's 50 inches long in total, plus the small resistor coil; it is a single strand of stainless steel, 24 gauge according to the service manual, but the wiring diagram doesn't show the little coil resistor...

New clarification - the little coil is not a resistor, but just the remnants of a wire nut...duh! Now just to find a replacement insulated stainless steel wire, but I'm striking out so far...why would GM use stainless steel instead of copper, and could I substitute? I was able to find single strand and insulated 24 gauge tin-coated copper...

I don't think it's stainless. Probably a higher grade of wire (something like tungsten but not that) so it can handle the amperage without melting for the thickness of wire. Also in that area is the fusible link, possible that? (designed to burn through)


:confused:

The fact that it has a wire nut indicates it's a custom add-on, probably done by someone who had no other wire handy at the time.

The loose output stud showing burn marks indicates a poor internal connection that was arcing over.

George

The alternator was toast, but all the copper wires between the alternator and the bulkhead connector were undamaged, including the fusible link; however, once the current reached the smaller gauge stainless steel wire (I've found information corroborating the type of wire), it couldn't handle that much and got so hot it burned all the insulation off and damaged other wires under the dash. I have a distant memory of putting the wire nut on because I cut it to reroute messy wiring there - I fully inspected all of the wires under the dash last summer when I did have a short in my courtesy lamp circuit. Unfortunately, I am striking out in finding stainless steel wire with insulation, so I may have to construct one...ugh!

Replaced the alternator, repaired the melted wires, constructed a new 24 gauge stainless steel wire with stripped insulation from a single stranded copper wire, and replaced the battery...it was a nightmare, but all is well now; one final thing is to finally ditch the OEM starter with a Powermaster 9510 that arrived today!

I feel fot you! Glad you got it all wrapped up. I recently went through tons of electrical issues on my 81 TA. Had about 50 hours into it.