I just bought an 88 Firebird Formula cheap. I'm working on fixing all the little issues it has so I can get it to pass safety and emissions. I have one problem left. Once this one's solved, work on restoration will begin in earnest. So, I hope you all can help me. Here's the situation:

All of the lights on the car work EXCEPT the dash illumination lights. When I examined the fuse box to see if the fuse was blown, I found that there ISN'T a fuse where there should be. There's not even a CONNECTOR for a fuse. There are no wires going to the place where the fuse would be.

I opened the dash and removed the instrument cluster. Once the electrical connectors were exposed, I used my meter to test the power pins on the connectors. No voltage registered with the key off, on or with the headlight switch on. I checked the dimmer switch and made sure it was all the way on. I even tested the dimmer switch with an Ohm-meter to make sure it's functioning properly. I tried to trace the wire (brown/white) from the electrical connector to it's source, but it's packed into a large cluster of wires that I can't follow without removing the entire dash from the firewall. I'd really like to avoid that if at all possible. So, any ideas? Has anybody run into this before? I did inspect and test all the bulbs and they are fine. I tested the continuity of the traces on the back of the cluster and they all test fine as well.

 

The fuse should have nothing to do with it if ALL the other lights work. Some of your interior lights (dome light/ map lights) are on the same fuse as your cluster lights.

 

The dome light does work. There's a light above the headlight switch and dimmer that doesn't work though.

 

if you replace the headlight switch it should fix it

 

possibly headlight switch or maybe the gauge cluster board. It is just a printed circuit board so maybe if you took the cluster out and cleaned the board contact paths or possibly another board to swap in and try out. Hope this helps also check for voltage at the power in on the plug for the cluster.

 

Well I bought a new headlight switch and put it in. No good. The problem persists. I tested continuity on the entire circuit board on the instrument cluster and everything is as it should be. I tested all of the leads on the connectors that go to the lamps one at a time and there's no voltage there even with the engine running and the headlights turned on. I inspected as much of the wire as I could and I couldn't find anything frayed, broken or cut. I'm at a loss.

 

Some new information in this mystery. Today I took the car for safety and emissions testing. While performing the emissions test, the car overheated. Needless to say, I failed. Here's why it's related. I tested things after I got the car home. The overheating occured because the cooling fan never kicked on even though the temperature guage was reading high. It's an electric fan so I can add that to the list of electric components that aren't working. I'm still trying to find a common link between what's not working. Tomorrow I will trace the fan's wiring to try and find the problem. Maybe it will help me find the dash light problem as well.

 

check the fusable links. i suspect u have a bad link and that is causing the fan not to kick on..

 

Ok. Fuseable links all look good. I've been doing a little more online research and it seems others have had this problem when after market stereos were installed. There is an after market stereo in this car that was installed by the previous owner. It's a hacked up job. They cut the built-in brackets in the console and used some kind of putty to mount the radio in place and keep the faceplate on. The wiring looks to be a little hacked up too. Does the circuit that illuminates the instruments go through thr radio harnes as well? Maybe this is where I should be looking. There is one wire on the stereo (blue I think) that is clipped and not connected to anything. And one wire in the car's harness that isn't connected. I don't remember the color. I'll look when i get home later. But does this bring anything to light?

 

On the stock radio wiring harness, there is a wire, to activate the brightness of the backlights on the radio, so that wire is somewhere in there, perhaps its grounded to something, and making a short.

Usually blue wires coming from the stereo are, amplifier remote turn on, and blue with white stripe is power antenna remote turn on.

So id look for the dimmer wire, if the wire is not connected to the stereo, the backlights on the stereo will stay on whenever the stereo is on (thats how i have always had mine, liek it better)

 

The radio back light does always stay on. Adjusting the dimmer doesn't affect it at all. I'll look at this more closely when I get home. Thanks for all the responses and help!

 

SUCCESS! It turns out the transistor in the "Remote Dimmer" was blown. The wiring on the after market radio is not even close to right. The ground wire isn't even connected to a ground! I suspect that this is what blew the transistor since they are on the same circuit. I found a replacement transistor at Radio Shack (NPN) and everything lit up like Christmas! As soon as I installed the stereo back in the dash, I blew the instrument fuse. I have pulled the stereo and replaced the fuse and everything is fine. Now I have to re-wire the stereo. Anybody have a good wiring diagram for the stereo wiring harness?

Thanks SO MUCH to all of you for your help.