This one is an odd one. I have been having some wiring gremlins with my stereo (no doubt shitty installation, it’s an aftermarket stereo crammed in a hole, assembled with dubious electrical taping). Anyhow, I went to pull it out, and knocked something out in there. I saw a spark (it was night time), and then I lost my cluster lights. I played with it later, only to find that my interior lights no longer work, nor do my front constant lights. The fuse (15A fuse) was popped, I replaced it and it has not popped since. I removed any possible loose wires behind the stereo, took it out completely. From what I can tell, all other lights - dome, rear running/brake lights, headlights, etc. work, and the door chime is functional. It is simply my cluster that does not light up. I have between 7-9v out on the dimmer switch, and a 12.4v in, which seems fine. Is there anything else anyone can suggest? I’ve never found an issue exactly like this yet. I’ve seen similar, but nothing exactly like this, and if there was, there was no resolution.
As a side note, I have hooked a 12v power supply directly to the + and - terminals of one of the backlights in the unit, and I DO get a backlight, so the bulbs themselves are good. The gauges also seem to all function correctly.
Okay, I’m gonna double-post with more information. At the right plug on the dash cluster, I have found Red/Black (we’ll call it pin 2) and Red (we’ll call it pin 4, not sure which order it ‘should’ go in)… Red/Black has +12.3v on it (battery voltage), and Red has 9.5v (which varies from 2-9.5v with the spin of the dimmer switch potentiometer). Red/Black is the ‘negative’ for the backlights (I have LED lighting, I believe the bulbs only work one way), and Red is the positive. It seems like my issue stems from Red/Black having battery voltage on it. I’m not sure why this would be, can anyone confirm if this is (somehow) correct or not?
Edit: Red/Black appears to go to the fuse box, according to the wiring diagram. What the actual f–k is going on here? Does the brightness switch control brightness not by providing a variable level of voltage directly, but by ‘lowering voltage’ by raising the voltage of what it supplies relative to the constant voltage?
Edit 2: Holy sh!t, it appears that it does! I have ‘temporarily’ fixed the issue by removing the dimmer control switch, and jumping the solid red and solid black (NOT the red/black) wires at that connector. I just used a paper clip. I will post further if I figure anything else out. I want to help anyone else that will search for this problem in the future (and I am sure there will be others) fix this issue. It’d have saved me a long drive home in the dark with a dome light, now we’ll pass the favor forward.