Club Cobra - Fried Electricals...finally punished for stupidity

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Fried Wires (dead starter circuit)

Today while I was adjusting the timing on ERA #164 the negative lead on the timing light slipped off the engine block. Then I got a white puff of smoke and the hiss of (I'm assuming) wire insulation burning off on the passenger side firewall. The car continued to run normally but I immediately shut it down. After a minute of inspection I tried to start it again. The starter circuit was completely dead. None of the fuses are blown (I wish they were, that would be an easy fix).

I'm not sure if the negative lead slipping off caused it, or if when it slipped off it caused the positive lead to shift and bridge a connection somewhere. The positive lead was connected to the positive battery cable near the starter solenoid since the positive battery post is impossible to reach (under the fender).

Wire #35 on the ERA wiring diagram has clear damage on the portion of it that is exposed near the firewall...I can't be sure if it was caused during the incident, or existing damage however. There could be other damage that I can't see.

I had a spare starter solenoid sitting around so I tried it and no difference. Any suggestions for where to start troubleshooting?

Grrrr.

Update: I tested the starter solenoid grounding wire (35/65) for continuity with an ohmmeter. Its shot. So I took a piece of spare wire and bridged the two termination points of the wire. No change. I'm off to continue troubleshooting.

Update #2: Well I'm stumped (granted it doesn't take much to do that when it involves electricity). Again checking for continuity with an ohmmeter all the other wires that come into the starter solenoid are intact back to their origin. The starter circuit isn't that complicated...I should be able to troubleshoot it, but its got me puzzled now.

Suggestions?

What a waste of half a day, but I finally solved it. The verdict is in, I am a certified idiot.

Just to eliminate the solenoid from the list of possibilities I replaced it with one that was sitting around the garage and I knew to be in working order. Unfortunately it was a 6V system solenoid and I didn't realize it. So then when I found the faulty wire and replaced it, it didn't solve the problem and I moved on to other sources.

Only after eliminating everything else from the list of possible causes several times did I take a second look at the solenoid. Put the old solenoid in, and what do you know it started right up.

Glad to have found the problem, and lucky that the faulty wire is one of the shortest and easily accessible, but not looking forward to surgery on the wiring harness.

Anyway, I'm guessing that when the negative lead of the timing light fell off the engine block, it shifted the positive lead so that it was connected to the positive battery cable but also touching the solenoid ground wire. The smaller gauge ground wire burned up quickly.

I think I'll just go through the hardship of connecting the positive timing light lead to the battery post next time :)

Wire 35 is simply a 10G ground from the engine to the firewall. You can replace it with any battery-type ground wire.