Never Underestimate the Power of Electrical Gremlins

**Power Surge** · **Never Underestimate the Power of Electrical Gremlins -** 12-20-03, 10:01 PM

Well, since I've supplied power to the Thundersnake after finishing the EFI wiring conversion, I've found that that car itself had some electrical issues unrelated to my wiring handywork.

First, the directionals stopped working. They HAD been working, but no more. So I checked into it and the feed fuse wasn't getting any supplied power, it was dead on both sides. I pull the fuse box apart, and trace the wire that feeds that fuse, and it goes to the ignition. So I drop the column, and pull the switch off. It's not switching power to that circuit when you turn the key. "No problem" I think, since I had a spare ignition switch from the 76. Ah, but not so fast, the plug is different on 77-78s

. So I literally split both switches open and made them into one good working switch. Ok, that problem is solved...

Next up, when you turn the parking lamps on, the right turn signal bulb in the dash lights up. I also noticed that the right front turn signal bulb is VERY dimly lit. So that's a good place to start. Quick test with the DVOM verifes a short from the parking lamp circuit to the ground. So now I start checking the rest of the circuit. I pull the headlamp switch plug, and check it there, shorted. So it's time to check all legs of the circuit from there. I disconnect the engine harness at the firewall, and it's still shorted, so that rules out anything forward of the firewall. Then I start checking the two areas behind the dash that wiring goes to, disconnect them, still shorted. That rules out the dash. I disconnect the harness that leads to the rear of the car, no more short. So now we know it's somewhere in that harness. Next plug in line, is the taillight harness. Disconnect that, no short in the harness running to the rear of the car. I check the taillight harness itself, shorted. Now I JUST installed this taillight harness, replacing the one that was in the car, because the sockets were crap on it. BUT, the problem was there with the old harness too. So I check the old harness from ground to the parking lamp circuit, and it's shorted too!

So all this work, and I have two shorted taillight harnesses. LOL.

COBRAIIW · 12-20-03, 10:24 PM

You DID remove the bulbs didn't you?
if you didn't,they WILL appear shorted.you are reading thru the filament.
Then again,some people say shorted when they mean they have an open circuit.
maybe i can help,having traced lighting gremlins before.

IICrazy · 12-21-03, 04:41 AM

yea i officially hat ignition switches, had to use 5 different books to figure out where to trace the wires, got it all figured out and now it runs for the first time in a month. all thats left is everything else needs to be wired

**Power Surge** · 12-21-03, 11:22 AM

Quote:

Originally Posted by COBRAIIW

You DID remove the bulbs didn't you?
if you didn't,they WILL appear shorted.you are reading thru the filament.
Then again,some people say shorted when they mean they have an open circuit.
maybe i can help,having traced lighting gremlins before.

Sheesh, you're exactly right. You know, sometimes when you spend most of your time dealing with the more complex automotive issues, you forget the simple basics. It's not the tail harness. And it only does it when you put a bulb in the right front socket. So I'm guessing there's a short somewhere in the front engine harness that's between the parking lamp and turn signal circuits. Oh well, back to the diag...

OH, BTW, I thought I'd share a tip with everyone. People always complain about our lovely fuse box location. I noticed that the fuse box and the part that clips into the firewall to connect to the engine harness unsnap from each other. So you could leave the plug in the firewall, and move your fuse box elsewhere if you wanted.

**Power Surge** · 12-21-03, 02:43 PM

Well, it's all fixed now. After all that it was just two bad front sockets. I replaced them with the newer style ones, with the snap in bulbs (3157s) instead for less problems down the road. I'll be converting the rear sockets over too, they'll just have to wait for now at $10 a socket. If anyone wants to do the same, Motormite part number 85895 in the newer style socket.

IICrazy · 12-21-03, 10:03 PM

Quote:

Originally Posted by CobraIILover

Well, it's all fixed now. After all that it was just two bad front sockets. I replaced them with the newer style ones, with the snap in bulbs (3157s) instead for less problems down the road. I'll be converting the rear sockets over too, they'll just have to wait for now at $10 a socket. If anyone wants to do the same, Motormite part number 85895 in the newer style socket.

do most auto parts stores carry these? (napa)? this will help me out a lot