Need some wiring help - Light switch

[ymerej71]

I've lost power to the head/tail light switch inside the cab... I'm in the process of untaping / untangling a mess of of wiring job that someone left for me to sort out so that I can trace the wires.

Question #1: are the headlights routed through the main fuse box? If so, I can't figure out where... although I did find in-line fuses under the hood.

Question #2: Does anyone have a diagram of the harness to the light switch so I can tell what color goes where?

Thanks in advance for anybody who can help me sort this out!

[hatzie]

I have 75-91 GM manuals scanned excepting 81, 82 & 84. What year is your truck?.

[donut]

Ditto, what year?
VetteVet posted up a diagram for '85-'86 for me (headlight issues) maybe it'll help you.
http://67-72chevytrucks.com/vboard/s...d.php?t=538109

[ymerej71]

Thanks, sorry for the delay... The truck I'm working on is a '79 GMC. Based on some of the fuse panels I've seen online, it looks as if this truck has the newer 1980 style fuse panel with the flashers on the top left and bottom right of the panel.

Yesterday I was able to trace the power (red) wire out of the light switch harness into the back of the fuse panel into the engine bay. From there it appears to run to the starter? Is that correct? I found that this wire was burned in half when i started pulling out of the wire loom which is obviously the problem with the power interuption. I ran out of time last night and didn't get under the truck so I can't for sure say that it was tied into the starter but that looks like where it terminates.

Any help you can offer would be greatly appreciated... I'm not great with wiring / electrical but willing to learn what I can and fix my own junk. Haha! Thanks for the help!

[hatzie]

Feed for the 79 lightswitch runs from a fusible link on the starter to the bulkhead plug.

The wire is burned at the starter??

[ymerej71]

Originally Posted by hatzie

Feed for the 79 lightswitch runs from a fusible link on the starter to the bulkhead plug.

The wire is burned at the starter??

Thanks so much for the help! It's not burnt right at the starter... actually 6-8" above it. By the looks of what I saw I'm thinking it might of gotten a little too close to the headers. The actual wire wasn't completely burned through, just charred a little, very brittle, and just broke in half.

[hatzie]

Originally Posted by ymerej71

Thanks so much for the help! It's not burnt right at the starter... actually 6-8" above it. By the looks of what I saw I'm thinking it might of gotten a little too close to the headers. The actual wire wasn't completely burned through, just charred a little, very brittle, and just broke in half.

Don't just replace it with a section of wire. That end of the wire incorporates a fusible link to keep the fire gods out of your cab.
I'd check the wire for shorts then take a look at this post... http://"http://forum.73-87chevytruck...?topic=11972.0