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burned ground wire revisited

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.

Reply to
JerseyJim
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Getting 12 volts is not really an adequate test. You could have a tiny piece of wire between the battery return and the engine and still get continuity. It still may not carry the necessary current.

You may get that even with the horn unplugged. The resistance in the horn is very low.

THe resistance could be on the order of 2 or 3 ohms and not noticable on your meter.

What you need to do is see if you get just a tiny bit more resistance between the wires and between the green wire to ground than you do through the black to ground. I expect the black wire of the horn is also grounded inside the horn.

Another test. With the horn unplugged, jumper a wire from the green wire to the battery positive. If the horn works the black wire is grounded inside the horn.

If it doesn't work also jumper the black to the battery negative and see if it works then.

Reply to
HRL

Stupid me!!!. Apparently like you said, continuity between hot and ground of horn is normal even with key off. Still don't understand that but can't argue with the facts.

Mystery continues..... Put horn wires back together and just for the hell of it figured I try to start it. Viola, it started right up. What the hell?. Only thing I can figure at this point is either I had a loose ground at the block (which I corrected by cleaning and tightening) or there is an intermittent shorting in the starter. But my best guess at this point is that you guys were right. Let you know if any more problems.

Thanks to all for your help. Regards Jersey Jim

Reply to
JerseyJim

I think the loose ground on the block is a good bet. Then the current from the starter would be looking for a path back to the battery. If the horn is internally grounded to the chassis it would then find a path that way. Naturally that wire could not handle the current.

I can't think of any short in the starter or for that matter any place else that could produce the high current in the horn return. This is assuming that there is a second smaller wire, other than the big one to the block, back to the battery.

Reply to
HRL

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