My amp meter used to give me irratic readings. Now it stays all the way over
to the right. I would like to get it working again. Can anyone tell me what is wrong and how to fix it?

My truck is 1985 f150,fuel injected, 302, automatic.

Thanks for any help.

SCTRT

 

Does it do it with the truck off, and not running, or does it only peg to the right when the truck is running?

It could be something as simple as a bad gauge, to something as complex as the wire from the alternator to the battery is bad, and most of the charging circut is being bypassed into and through the ammeter. (Not good! could cause fires.)

 

Theres a little old lady locally that drives a 66 f series, it was about to go up in flames, the aftermarket amp meter was melting, and the insulation was burning off of the underhood wires. I got the battery cable off before it went up.

 

Yes, that is why the shunt is so important. Do a search here for shunts, I'm sure you will find posts by me explaining the dangers of bypassing or not using the factory shunt. Or for that matter using a aftermarket ammeter without installing the needed shunt.