Instrument lights...

jsteed

CJ-8 Member
CJ-8.com Member
City
Seattle
State
WA
#1
I've been trying to work through this rats nest of wiring to figure out how to get my instrument light to work. Played with dimmer while checking voltages, checked 3A fuse, then measured voltage across fusebox for the acc light fuse... 0 with lights on. Interesting. Based on wiring diagram, I believe there is an instrument lamp wire that comes off the headlight switch that should go the fusebox before going back to lights in dash. Of note, they have flickered on and off before, so I could also potentially have a bad ground, and there are plenty of ground wires hanging from back there that are abandoned. But with the zero volts across the fuse block for panel lights, it could be no supply OR no ground.... right?
 

bigwalton

Picture cravin' AK Postal nut
Staff member
SOA Member
City
Dexter
State
MI
#2
I've been trying to work through this rats nest of wiring to figure out how to get my instrument light to work. Played with dimmer while checking voltages, checked 3A fuse, then measured voltage across fusebox for the acc light fuse... 0 with lights on. Interesting. Based on wiring diagram, I believe there is an instrument lamp wire that comes off the headlight switch that should go the fusebox before going back to lights in dash. Of note, they have flickered on and off before, so I could also potentially have a bad ground, and there are plenty of ground wires hanging from back there that are abandoned. But with the zero volts across the fuse block for panel lights, it could be no supply OR no ground.... right?
You checked it across the fuse, did you check from each side to ground? That’s how you’ll find if there’s current being supplied.

Instrument lights are notoriously bad grounds and if you had flickering that’s where my money would be.
 

jsteed

CJ-8 Member
CJ-8.com Member
City
Seattle
State
WA
#3
Turns out it's a bad switch. I checked each side of the fuse block to known good ground and it was zero, but spiked to about 4 volts when I touched the dimmer knob. Turned it one way, zero, the other way, zero, but saw a jump somewhere in the middle. Fiddled with it a little and got 12v at a very specific spot. Problem identified. Thanks!
 
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