Hey guys, I have a 2002 Duramax. Ever since I have had it the voltage will drop down to around 12 volts or so when letting of the throttle. It does it in situations such as letting of the throttle to turn into a driveway. The headlights will dim and the guage drops for a couple seconds and then it picks back up to normal. I have had the dealer check it out and they have found nothing wrong. Any ideas?:grd:

Maybe the voltage regulator is a little slow to respond? My wife's trailblazer does this when you hit the brakes at highway speeds, but only when running all the lights, etc with a fairly heavy load on the alternator. Everything dims for a split second then back to normal. It's been doing it since new, too and "no trouble found" when the dealer looked at it..........

Its a wild guess but sounds like a regulator problem or one leg of the brdge rectifier in the altenator is going bad.

I have similar issues with my 02. If you have the lights on and try to roll down the windows, the lights dim way down. I've had both batteries and alternator checked and I checked all my power wires. Can't find anything wrong.

My '03 does that too. The regulators are just take a second or two to react and the voltage picks right back up... It's normal...

It's even more evident with the six-speed. At speed, when you depress the clutch and let off the accelerator (immediate engine drop to idle), my A/C fan will slow for a second or two... then all is back to normal.

L8r...

Ground problem.

Idahofox

what he said

And it's not normal. Your batteries after a few minutes should be up to alternator voltage and be capable of running several accessories at the same time. If things go dim when you let off the throttle your batteries are not up to 14+ volts. Later! Frank