Is there a place where i can get a wiring diagram for my 70 GMC Jimmy? This thing has so much screwed up, i don't know where to start. Would prefer something free on line, but will buy diagrams if i have to. Pretty much need the whole layout. One of the funky things that happens is when the lights are turned on, the fan will only work then. The headlights will not light up when it is doing this. Also this situation comes and goes. When the lights work the fan works normally. Also, the wires for the temp sender and the gas tank sender are gone. They were clipped at the firewall i think, but want to make sure. Green for temp sender and brown for tank sender. I decided to just pull the harness and start checking it wire by wire, but would like to make sure that everything goes where it is supposed to. Thanks for any help.

Forgot to mention, when the lights are not lighting up with the switch in the on position, if you turn it off, the the fan will also turn off. All i have to say is Gremlins. :whine:

My idea of gremlins would be "intermittent electrical problems caused by old wiring and connections". Your problems sound more like "previous owner messing with something he wasn't qualified to touch".
Does your wiring look original. I'm guessing not. I'd start by getting a parts catalog from LMC truck. http://www.lmctruck.com/icatalog/cb/t1.html
They have manuals and parts to fix your problems.

After going through my entire interior wire harness i found 3 wires that were bare and were shorting. I just removed part of my engine wiring harness. This would be the part that would go to the headlights and the alternator. I have three red wires that spit off from the one that is fed to the fuse panel. One goes to the alternator, one to the regulator and the third startes to go towards the battery and is cut off. Is this wire supposed to be hooked directly to the battery or does it go somewhere else? One of the other problems my Blazer has is that it will not shut off when it is started with the key. I am thinking it has something to do with the alternator feeding the engine and not letting it shut off. Thanks for any help you can give me.

My idea of gremlins would be "intermittent electrical problems caused by old wiring and connections". Your problems sound more like "previous owner messing with something he wasn't qualified to touch".
Does your wiring look original. I'm guessing not.

My wiring is original, but has been cut, spliced back together, etc, etc. Also noticed that i have a ground wire that my headlight grounds go to on the drivers side. This wire is also cut off a few feet from where the grounds mount against the core support. I would guess that this wire also is supposed to go to the ground side of the battery for a body ground. How somone was able to drive this thing before i will never know.

local libraryies sometimes have this info in refrence section mine has nice set of mitchells manuals with wiring