Topic: wiring

[kendupree]

Well, I am new to this so bear with me. I am having a problem with the wiring in my 10th anniversary Trans Am. The dash lights are out and the dome light comes on dim every time I hit the brake petal. I also have no brake lights. The taillights and headlights and marker lights all work. I also lost the clock on the radio. Any suggestions on where to look? I have checked the grounds on both sides of the core support, they are good. I cleaned the plug terminals in the trunk and made sure I have a good connection. I also re-grounded the black wire in the trunk for the taillights. Any help at all will be appreciated. Thanks.

[Kire]

You may have already done so, but check to make sure all the fuses are good and and no wires are jammed in by a fuse that might cause problems.

[78ta]

May be two separate problems. Check the ground to the dash for the dash and radio clock light problem. The dash ground is down under the dash on the drivers side near the courtesy light. It's a 1/4 or 5/16 inch hex screw that screws into the dash metal which is thin so the hole is easy to strip causing a bad connection. It can also just vibrate loose.

The fact that your dome light comes on when you hit the brake pedal makes me think you've got a bad ground to the brake lights and or a bad brake light bulb. The filament in the bulb can go bad in such a way as to not light the bulb but still provide a current path to ground though it has a high resistance or it would blow a fuse. If there is a path to ground somewhere, the current will find it. In your case, it sounds like it's going through the dome light.
  Pull the brake light bulbs out and hit the brakes to see if the dome light comes on. If it does NOT come on, check each bulb and replace any bad ones.
If you don't find any bad bulbs, verify that the brake light sockets are ok and that the ground for each socket is a good ground. 

[brian c]

I agree with Randy and Kire.

Check your dash ground. What I did for mine was run a dedicated line from the ebrake assembly up to the gauge pod. There's a terminal on the back marked GND (ground). That cleared up a host of issues for me with the gauge pod.

I see that you checked (2) of the typical grounding points but you may want to check a few more to make certain they're in place and have good connectivity...

1. Battery to engine block.
2. Engine block to firewall. It may or may not be in place. If the engine has been out of the car its possible this connection was not put back afterwards.
3. Tranny to front subframe. If there's been any tranny service or engine service this too might have been overlooked and not reinstalled.

Remember, when making grounds, sand down to bare metal, attach your wire, and then you can top coat with paint to prevent rust.

[kendupree]

Thank you all, I will soon get to work. I will also post what I find for the next guy.

[kendupree]

well guys, I have done all of the above and I found the dash light problem is separate from the brake light problem. The dash light problem is the circuit board delaminated on the guage cluster and shorted.The brake light problem is still a mystery. I did find that it is also affecting the wipers. Hi works, but low and delay are intermittent. I chased the orange wire that powers the brake light switch and when the problem surfaces, that orange wire has no power. According to the wiring diagram, the orange wire is # 40 and goes from the fuse block to the rear harness connector where it powers the trunk light, then back to the brake switch then to the radio display. In my car this does not seem to be correct and I am having a hard time chasing that illusive orange wire. Can anyone help? 

[brian c]

If you have your driver's side sill plate installed its time to remove it. Just unscrews. That hides the wiring run from the fuse box back to your trunk. Now, considering the car is 30 years old (give or take) its entirely possible it's been hacked elsewhere so you *may* need to pop off the driver's side sail panel and the trim panel below it to see the entire run.

I'd also look under your dash to see what's been cut into the factory harness. Things to look for...wire ties, electrical tape, shrink wrap, different colored/gauge wire spliced it - where they shouldn't be.

Pics would help in this case.  Under dash, in the engine compartment, and in the trunk.