burned ground wire

Lights going dim when starter or solenoid is activated is a sure sign of a bad (high resistance) battery circuit connection. The starter was trying to get its current through the horn ground which was not capable of carrying the current. So it overheated and burned the insulation. Check the connection at both end of the ground cable, clean metal and tight should do nicely. Then try it again and let us know what happened.

George Vigner>I'm stumped. My starter wenton my 89 C10 so I put in a new one.

Guess I need to crack open a book on the workings of electric current because I'm drawing a blank as to how or why electric current would even be passing through a GROUND wire, rather than the hot wire. And why the horn wire in the first place. Seems to me that the horn and ignition circuits should not be meeting each other unless they have shorted together somewhere. And that most likely would be in the steering column.

The horn ground wire runs up behind the passenger side parking light where it connects with several other ground wires at a single joint. Then one wire runs from that joint to the passenger side fender ground screw. If all these wires are joined into a common ground why is only the horn ground burned to a crisp?. I'm going to check the engine block ground tomorrow and rewire the horn ground. BTW, the horn still works. I'll see what happens then. Might even break out my multimeter and try to figure out how to use the damn thing. I'll let you know what I find.

Thanks for the tips Jersey Jim

I go along with George.

My guess is that the horn might have an internal ground to the chassis as well as the ground wire. Is there both a heavy and a small ground wire to the battery? If so and the heavy ground wire has opened perhaps the current is trying to get back to the battery through the horn chassis ground.

Jim, ALL the starting current has to pass thru the ground wire to get back to the battery, that is what completes the circuit. The neg term of the battery is connected to the frame which makes it easy to "ground" everything else in the vehicle. The frame is the return path for electrons to the battery. That is why you only need a "hot" wire to connect up accessories and then "ground" them with the black wire to the frame. As to why the horn wire burnt....my guess is that the starter ground was bad and the shortest path back to the battery was thru the horn relay. Mike

I think I'm on to something. I put a voltage tester between positive battery and engine block and got 12 volts. So ground seems to be working. Nevertheless, I cleaned all ground points and tightened them.

I then put a continuity tester on the horn wires. Green and black. Even with the key off, I have continuity between the two wires. I then connected the tester between the chassis and the green hot wire to the horn. CONTINUITY again. Even with my limited knowledge of electronics I know this can't be normal. Something is grounding the positive horn wire to the chassis. I note that there is no point where the two horn wires touch ( the positive runs over to the drivers side and the ground runs to the passenger side.

Oops!!. Almost forgot, perhaps they may be fused together inside the horn connector or horn itself. I'll have to check that next. If that checks out I'll trace the horn positive wire back to the steering column and try to find out where it's shorting.

Jersey Jim.