i will drive along and the volt gauge on my 86 iroc will drop down below the 1/4 mark. after driving a little while longer it will jump up able 1/2.. when the gauge drops the headlights dim pretty bad....what could cause this ?? please help!

thanks
ryan

 

Sounds like there is a power wire that is shorting out to ground periodically. This direct short can cause a large current draw, dropping the voltage at the alt. Try to find any large cables near the battery that are chafed and possible shorting out. This sounds like it is happening near the battery because no fuses are blowing, however if there are circuit breakers in the circuit, look downstream of thoses. They could be opening the circuit from the short and then resetting, causing the intermittent nature of the problem
Good luck.

 

Yeah, it sounds like you have a ground some place or you have an alternator getting ready to die.

 

Check, clean and tighten all the connections...

93Z Will