Help Diagnosing Electrical Problem

1969VAGTX · Jun 11, 2026

As some know, I had a fire under the hood of my GTX back a few months ago. I have replaced and repaired what obvious damage there appeared to be. When we first went to start it I had to tap the single wire coming out of the passenger side of the ballast resistor. Then it fired up and ran fine. When I went to move it into the garage it completely died. Now it has absolutely no power whatsoever. We tested the battery and it is fine.

It seems one option could be a dead short somewhere. But nothing changed and no apparent wires were damaged by the fire. The car is completely dead on its feet with no power at all (no lights or anything). Would appreciate some thoughts on what might be the culprit.

493 Mike · Jun 11, 2026

Are all the ground wires doing their jobs (continuity)? Is power available at the starter relay stud? Was the fire caused by electricity or fuel?
Mike

pnora · Jun 11, 2026

1-Fuse link
2-Bulkhead
3-Ammeter

kiwigtx · Jun 12, 2026

1969VAGTX said:
When we first went to start it I had to tap the single wire coming out of the passenger side of the ballast resistor. Then it fired up and ran fine. When I went to move it into the garage it completely died. Now it has absolutely no power whatsoever. We tested the battery and it is fine.

Is the connection 'good-n-tite' like a German torque wrench?

I had loose spade terminals on a ballast resistor that caused the engine to cut out without warning.

Re-terminating solved the problem.

Bird 426 · Jun 12, 2026

#4. I have had an off and on charging problem for five years or so. Just couldn't nail it down, it seemed to change. One spade terminal on the alt seemed loose , saw some arking, didn't like the looks of it so I replaced it, knock on wood, it's been good since. They just need to have a tight slide fit. Time will tell if that was it or I am am waiting for the next time! At least I have gained confidence that after a few very short drives, that I can drive it somewhere now.

Dennis H · Jun 12, 2026

Bulkhead.

1969VAGTX · Jun 12, 2026

Car ended up starting up and running just fine again this morning. Totally confounding. Fusable link and ammeter appear to be fine. Going to check all the connections in the bulkhead and around the firewall. I had also put a new alternator on last winter, so I will go back and take a look at the connections there as well.

furyus · Jun 12, 2026

If you tapped on the ballast resistor, and it started working, then that's the place to start. Are the terminals crimped? I always solder all my terminals.
Try replacing the resistor if it's not the terminals. It could have issues.

Bird 426 · Jun 12, 2026

Soldering is good, as long as the solder doesn't wick back up into the insulation, it's a break point. Never worried about it until I built an airplane, high vibration environment. Strain relief is better, unless you have to solder.

furyus · Jun 13, 2026

Bird 426 said:
Soldering is good, as long as the solder doesn't wick back up into the insulation, it's a break point. Never worried about it until I built an airplane, high vibration environment. Strain relief is better, unless you have to solder.

I've never had a failure on soldered terminals. But, I've had plenty with just crimping. And we're talking about two different things.

threewood · Jun 13, 2026

As long as the wire is secure and doesn't flex at the solder joint edge it will be fine. I too prefer solder joints.

Help Diagnosing Electrical Problem

1969VAGTX

FBBO Gold Member

493 Mike

FBBO Gold Member

pnora

FBBO Gold Member

kiwigtx

International Mod of Mystery

Bird 426

FBBO Gold Member

Dennis H

FBBO Gold Member

1969VAGTX

FBBO Gold Member

furyus

Well-Known Member

Bird 426

FBBO Gold Member

furyus

Well-Known Member

threewood

FBBO Gold Member

Similar threads