I have an 08 H3 when I brake the head lights will flicker are diem just for a brief second.
This happens about 1 out of every 3 times I brake. The head light switch stays in the autoposition and it is always dark out not dusk, I dont think it is a sensor problem. That being said has anyone run across this????? I had an 06 H3 and I did not have this problem.

 

That is because on the newer H3s with the 3.7L the alternator actually "shuts off"- doesn't draw power- when there is low power consumption. When needed, the alternator kicks back on, and like any electrical system, there is some lag. It was done to save gas but it will not cause any harm.

 

Assasin is right, the computer does regulate the alternator on your H3, but the headlights shouldn't flicker or dim. There's a hundred possible problems, from bad grounds to a bad pcm, but you should have it checked out.

 

Good information.....I called the dealer they said they hear of this once before but never did
find out what caused it. Just thouhgt it was strange.

 

Well at least you reported it, and let me say thank you for that. Its going to be people like this forums members that help maintain Hummer as a good product. I just hope they don't pull the plug on them and stop making this wonderful product.