I own a 2002 3500 CC LB duramax. When I am driving and let off the accelerator pedel the lights all dim and the volts meter goes down abit and then it goes back up again. It doesnt do it every time but when it does its a pain because the dash and headlights dim. It has done it since I bought it new and the dealer said it was normal. They said it was a surge protecter. Has anyone else had this problem with their trucks or is it normal?

yes i had the same problem it was a bad batt. i put a load on the batt one at a time and found the batt was bad. after i replaced the batt the problem was fixed

I see wher you have might have been confused with diagnose,Moving to electrical,for better responces