[tikler]

Gotta admit this is a new one for me. The car is seldom driven, enough to keep the battery and fluids ok. So I get in it a few days ago and notice the interior lights come on every time I depress the brake pedal. No brake lights, all other lights function as normal. I pull the bezel, unplug the light switch, see no obvious problems and put it back together. Now everything works. For one drive then it starts doing it again. Any ideas? It's gotta be a clue that unplugging the switch had an effect. That or something close to the switch. Could the ground strap between the switch and cluster have this effect? I'm perplexed.

[FrankieT/A]

Check the fuses

[tikler]

Fuses are good. This weekend I'll go back in with a meter and a diagram and see what I can find.

[Alvin]

IMO I'd check the grounds, and the door light switches. They (door swtchs) have a single power wire with grounding to the body - completing the circuit - via the thread edge of the switch. In the past I've had weird electrical issues that traced back to a simple door switch bad ground.

Since your car sits inop ground connections may "flash rust" corrode. Dielectric grease can be used for long term solution. WD-40 etc usually evaporates and problem returns.

Check the brake light switch circuit for same issues. Hope this helps.

[tikler]

Excellent pick man. The diagrams show possibility for just that. Had to powdercoat all day today. I'm going to look at that stuff tomorrow

[Alvin]

Originally Posted by tikler

Excellent pick man. The diagrams show possibility for just that. Had to powdercoat all day today. I'm going to look at that stuff tomorrow

In the past (way back in the early '80s) I used 1/4 drive ratchet to remove switches and a MINOR amount of corrosion was on the switch threads where it screwed into the body on the drivers side. A simple wire brush cleanup and shot of WD-40 did the trick back then. You can visually tell if it is a bad ground, also, if when the dome light comes on, it's a dim - less than full candlepower light output...

Hope that's what is causing your problem. Keep us posted with whatever you find as the cause.

[tikler]

You got it man. I've had this one a long time, I guess I'll probably never let it go. My stuff gets addressed last usually so it's got small nagging issues. I'm hoping to correct that in the ongoing future. Thanks again. I'll see what those spots do for it tomorrow and get back to you.

[camerjeff]

I 2nd the grounds on the tail lights, I had a 69 GTO that for awile had front brake lights, when I hit the brakes the front turn signals came on bright and steady. Ended up being bad grounds on the tail lights Corrosion and frayed wires. I ended up putting separate ground wires to each socket. And it cured the problem.

[Alvin]

Good stuff.

FWIW - my "bad ground issue" was on a pristine rust free '78 T/A... I cringe thinking of what our northern brethren have to deal with with this kind of "simple stuff" corrosion issues, etc.

[tikler]

Interesting. The door switches checked out. I haven't started tearing back into the dash yet. I'll check those grounds and connectors in the back first I think

[Alvin]

Just remembered: you may also want to check the wire loom connection coming into the drivers side interior toe board area main fuse block. With bright light look for any wires that the insulation, although NOT scorched or discolored in appearance, may have melted and flowed from previous overheating of the circuit ( Look at the wires above the fuse block just before the connect to it).

The result can be two circuits going direct to ground PRIOR or PAST the fuse block. My car never blew a fuse when this occurred...

Had that happen one Thanksiving Road Trip... A simple separation of the fused wires where stuck together and re-isolation of bare wires fixed the problem for me. The damage was ABOVE the factory connector connection into the fuse block.

Also, check the main engine side firewall wire connector to fuse block if all other options fail to eliminate the issue. It's usually just a simple corrosion or short issue in my experience. That's what makes it so much fun?

[tikler]

Nowhere is easy to reach under a 2nd gen dash. I'm having to come out every few minutes to keep from turning into a human pretzel. No luck so far, grounds in the trunk and connections look ok. Even the fuel sender ground. When I recover I'll get back in and check the wires around both sides of the bulkhead connection. I hate electrical

[Grand73Am]

Since it happens when you push the brake pedal, one thing I'd look for is loose white wires around the brake pedal pivot area. If it's pinching a white wire when you push the pedal, it can ground the white wires and cause the dome light to come on, since it works off of grounding the white wire.

[tikler]

Six hours later, success. Combination of one rotten rear light socket, and dome lamp feed wire from the trunk junction. The dome lamp wire was grounding out and screwing up the brake lights and dome lamps

[Grand73Am]

Good to know the reason in case it happens to one of us too. Thanks!

[tikler]

I'm glad I can contribute to a board I've used so much. I have to add that the Chinese made fuses aren't as sturdy as what we're used to.

[Alvin]

Originally Posted by tikler

I'm glad I can contribute to a board I've used so much. I have to add that the Chinese made fuses aren't as sturdy as what we're used to.

Thanks for the update!