Help!...Cab Electrical Problems from HELL!!!

[dyno]

I'm working on cleaning up my 1980 K20 4x4 cab wiring and I cannot figure out this problem. I have all the interior and dash torn out and all wiring is visible.

Instrument illumination, wiper switch and fuel gauge all have a related problem.

1. Wipers only work if you push wash. Tried 3 switches.

2. Wiper switch light stays on all the time with ignition on, instrument illumination lights off.

3. When Wiper switch is plugged into harness, fuel guage drops to empty, unplug it and fuel gauge comes back up. Push wash, wipers work and gauge comes back up, release and gauge goes to empty.

WITH WIPER SWITCH DISCONNECTED:

4. Rotate headlight switch to turn on instrument illumination, fuel gauge drops to empty. Turn them off and fuel gauge comes back up.

I have spent 4 nights trying to figure it out and I am stumped.


Thanks,

Dyno