Chasing Instrument Light Short

[olds70supreme]

Hello,
After years on hold, I'm finally back working on my '75 Starfire. When I touched it last I had pulled the dash for some R&R, so I have easy access to the wiring. The instrument light circuit blew fuses and I want to fix this before putting it back together. It doesn't look like it's going to be easy though, as all of the lights power and grounds look to be wired in parallel. I don't see any connectors to disconnect parts of the lighting harness from the rest either, so aside from unwrapping all of the tape from the harness and visually inspecting, what are my options? I'm a novice at auto electrical but willing to learn. Is it possible that the light switch itself it bad?

Thanks.

[monzaaddict]

i am no expert either but the circuit seems to consist of the dimmer in the light switch and the bulbs for instrument lighting. my guess is short in the switch.
https://www.youtube.com/watch?v=ryuwnYO9GUw&t=390s

if the dash is hanging disconnected from metal dash structure, then your ground is not grounded. the ground wire connects to screw at the harness connector that goes to back of car (drivers side right near large bolt that attaches to dash structure).

[monzaaddict]

the radio light is also part of circuit. Is the cut wiring dangling and making contact with metal dash frame?

[olds70supreme]

If I test resistance across the switch, what value do I look for as too high?

[cosvega76]

A high resistance is not a short. A short is near 0 ohms, and that will blow the fuse.


Chuck

[cjbiagi]

A switch doesn't normally cause a short, it is either open or closed, neither is a short. It is just allowing current to flow through it.

[dindin]

Not sure if you fixed this but the parking lights are on the same circuit..could be something related to parking light wiring or sockets causing issue.

[olds70supreme]

Found the issue. After mindlessly focusing on the wiring and sockets behind the dash, I smartened up and removed the fuse. Continuity testing on the green-wire leg of the fuse terminal showed random intermittent values with occasional short I fixations. Unplugging the switch eliminates these. New switch arrived yesterday and all is well as proven by successful test while powered up.

[74_Vega_GT]

~ Congrats on your troubleshooting. At least you didn't have to dismount the fuse box and disassemble it to replace or fix a short there like we did. It was not fun.