I thought is was the switch block as it was stuffed. The rheostat wasn't making contact and the ceramic was brittle and broken. So ordered a replacement switch. Installed, put in new 5am fuse. Hit the lights, bam, fuse blows. instantly. So it's not the switch. So now I am at a loss. What would be causing this. It's literally the instrument panel lights only. The ones that cast a white light on the instrument panel. All other panel lights (indicators, oil, gen light etc) all work perfectly. Just the instrument lights. Loom is all wrapped in tape from factory. it lietrally goes from switch to fuse blow to instrument panel, so very little wire and I cannot see anywhere where it is shorting out. I'm now starting to suspect the fuse block may be the problem. Is it shorting ? Any thoughts before I hand it over to a real expert..... I'm really no expert when it comes to wiring...black art.
Wiring issues can be very frustrating, especially when it is not your forte. I agree with your deduction, it is time for you to hand it over to someone who has electrical troubleshooting skills. My only other suggestion is to take the dash cluster out and inspect it very closely for shorts and while it is out also inspect the dash wiring harness. The hot wire to the cigarette lighter is often cooked pretty badly and can have caused issues with near by wires.
Well, on the bright side (no pun intended), its a dead short to ground, so its easier to diagnose than an intermittent issue. It should be a pretty straightforward circuit. On the later model cars, its the gray wire. If you can get to the back of the cluster easily, start unplugging light bulbs. Does it have a printed circuit board?
Another thought... are you sure that the circuit is rated for 5 amps? It might be the wrong (too low a value) fuse?
Circuit is 5amp. Says on fuse block 5amp fuse and in service manual as well. I have pulled the harness at back of cluster, all wires look perfect and fine. I just swapped out the switch for the lights with a brand new part, still blows the fuse when lights turned on. I'm going to pull all the globes and just check it's not one of the globes. I did change them all over to LED while I had it apart the other day. But bottom line this is now beyond my skills. Will do the globe check, if it isn't a globe causing the issue then off to he experts....
