I've had this problem for almost a year now. Its intermitent and has never been a real worry.

What happens is at night when I have my headlights on and press the brake pedal, my voltage will dip down bigtime. My headlights go dim too. As soon as I take my foot off the brake pedal, the voltage goes back up and its ok. I have had a 6 month old alternator and went ahead and replaced it thinking that may have been the problem. It wasn't.

Anyway, its intermittent. Sometimes i'll have the brake pedal on and it'll be fine, a few seconds later and poof, voltage dips. It never dips to the point where the car shuts off, but it also causes my stereo amp to click off for a few secs.

If you guys need more info, leme know!

------------------
3rdgen.org - Real Cars, Real People, Real Fast!

 

Sometimes when I tap my brakes my headlights will dim, but my volt meter doesn't move. As with you, it's intermittant and has never caused me any worry, so I've made no attempt to figure it out.

------------------

The IROC Homepage
<A HREF="http://www.rit.edu/~jli4307/camaro" TARGET=_blank>
View the restoration of an 85 IROC</A>
Custom Thirdgen Subwoofer Enclosures
"I didn't know a bored out Ford could go so slow" -Shenandoah

 

You have a grounding situation associated with your brake pedal. The wires to the brakes are grounding out due to chaffed wiring or the physical movement of the brake pedal is pushing on a wire under the dash causing it to ground out. I would check under the dash first. Move the brake pedal and see if it is contacting any other wiring.

 

See this post.... https://www.thirdgen.org/techbb2/sho...threadid=79918

Beleive it or not, whatever I dis while pulling out the panels, all the problems went away. lol.. Maybe something was loose or shorting like you said.

 

Glad to hear that you were able to fix it. Electrical gremlins are a PITA. My headache turned out to be the aftermarket radio the nut before me installed by twisting the wires and black taping them. It was grounding on the dash.