I'm pretty inept at auto electrical issues, so try not to laugh :)

I've been chasing a weird electrical problem on my 64 C10 truck, and to that end, I'm trying to get a clear understanding in my head of where the power to various accessories comes from. As best I can tell, at the fuse panel, there's some stuff that has 12-volts all the time (does this power come from the horn relay?) and then some other stuff that is keyed 12-volt (either ACC or ON position). Where does the ignition switch get 12-volts from?

As best I can tell, there's only two positive wires coming off the battery...a small one over to the horn relay, and obviously the fat one to the starter. Surely all of the power to the fuse panel doesn't go through that small wire from the horn relay?

Surely all of the power to the fuse panel doesn't go through that small wire from the horn relay?

Yes it does. Here is a pic of later models, the 12g red feeds everything, fuse box, IGN switch and headlight switch.

http://www.chevelles.com/showroom/data/500/medium/Original_Chevy_system.jpg

Cool, thanks. Is it fair to say that a whacked horn relay could cause intermittent electrical gremlins in other systems?

Not sure how 64's are set up, but on later models, the horn relay buss bar is only a connection point. Just make sure the bar and terminals are clean and tight.

What kind of problem are you having? I have found the alot of strange electrical problems are caused by loose or bad ground conection. We like to think of the positive wiring and forget that every circuit must have a ground return path. Gary

What kind of problem are you having? I have found the alot of strange electrical problems are caused by loose or bad ground conection. We like to think of the positive wiring and forget that every circuit must have a ground return path. Gary

This is very true. You can attribute the majority of electrical troubles in these cars to poor ground connections.


Rocky

I found the problem, and it was a bad ground. I recently replaced the wood in the floor of the bed, and the hardware kit comes with rubber cushions to use at the bed-to-frame mounting points. Even though the truck originally had some type of cushion at these mounting points, apparently the new cushions negated the ground to all of the rear lights...stop, tail, and turn signal. I made a ground strap of 10-ga wire, attached one end to a bolt through the frame and the other to an existing bolt used to attach the bed side panel to a filler panel, and all is now well. Thanks for the help!