No Instrument Panel Lights

[gm muscle]

I have a '77 Trans Am with non functioning instrument panel lights. I noticed this after I had a stereo system installed but the lights may not have been working since before the installation as I rarely drive it after dark. I replaced the fuse (tiny fuse) but still no lights. I still plan to take a volt meter to the fuse panel and see if there is power to the hot side. But what next if there isn't?
What else should I do?

[Wallington]

Also, confirm it has the ground strap attached next to headlight switch. Or run a ground lead to metal case and see if any change.

[gm muscle]

The ground strap is attached to both the switch and instrument panel case.

[76Tranz]

sometimes it could be as simple as twisting the headlight switch (rheostat) back and forth a few times to make good contact with the dash lights. My cars do that sometimes after not using for a long time and twisting the rheostat turns them back on. Just a thought.

[gm muscle]

Yeah, I tried dimming and returning to full brightness to no avail. I did check the fuse panel and there is battery voltage when I turn on the parking lams. Unfortunately there isn't battery voltage on both sides, which would indicate that the fuse is blown or inoperative...I just replaced the fuse last week.

I guess it is possible the fuse blew when I activated the switch or the new fuse was bad to begin with. I think I have one more fuse, so I'll go for some more. You buy them in an assortment package, so I'll buy a bunch of fuses I don't need (I have around 20 fuses of 10, 15 and 20 amps. I've got some errands to run but I'll report back later today. 

[gm muscle]

Well, I've got bad news...there is definitely a short because it blows the fuse.
Actually, with the first fuse I replaced there was no link in the fuse to blow. 

20221007_201612 by Jose Mireles, on Flickr

 With the next two fuses i noticed a dim light (spark) coming from the fuse when I turned on the switch. Its hard to see but if you enlarge the picture, you can see the burnt link.

20221007_201811 by Jose Mireles, on Flickr

Time to break out the wiring diagram....any advice is greatly appreciated. 

[Wallington]

Try the main cluster circuit board with any worn or cracked areas touching where they shouldn't. Perhaps remove all bulbs, check and replace one at a time while testing.

[gm muscle]

I got underneath the dash this morning, which meant I had to remove the driver seat and center console (I'm not 18, skinny or limber anymore). The only thing I did see was that the printed circuit is coming apart. I decided to stop there and place an order for another one.

[Wallington]

Good find. In order to get the main gauge cluster out you need to also drop the steering column down. You can possibly have it just supported by a few threads in each nut but original may not be the same as mine, you don't want to scratch the column just because you didn't drop it enough. Don't forget the speedo cable as well as the plugs.

[gm muscle]

Thanks, I've had it out a couple of times in the past. I'm going to make an appointment with a reputable auto electrical shop near me.

[firebirdparts]

That's certainly the right thing to do.  The printed circuits are trouble prone.

I'll just throw in here, also, that the panel lights circuit has a wire that went to the old radio.  The old radios had a little incandescent bulb that came on and dimmed with the panel lights.  You might ask yourself what the radio installers did with that wire, considering.  Where is it now.  It's gray.

[gm muscle]

Funny you mention that gray wire....the technician who has been working on the car called me to give an update on the work done (there were a few more issues I needed addressed). He said the gray wire was used as a ground! 
He saved the connector used and a bit of each wire to prove that they indeed screwed up. I feel vindicated. I need to speak to the stereo install shop owner that was emphatic in denying they had anything to do with the short.
So the printed circuit was replaced along with all of the bulbs, the short was repaired and the wires on the window relays were extended to use with the center console.
I'll update if I find out anything new.

[gm muscle]

Well I spoke to the stereo shop owner and spoke to him about what the electrical technician found. He quickly became defensive and rude. He was saying how it is an old car, what did I expect, it probably already had a short to begin with,  it was their word against his. He also chucked the connector into the parking lot (the one he used to connect the stereo ground with the cigarette lighter bulb wire.
I simply picked up the connector, said good bye and left....there was no point in arguing. Lesson learned.