headlights pulse like a police car, ive had cars actually pull over for me also at the same time the alternator gauge would go down and dash lights would dim would. Chevy dealer would always fix it with a new alternator blaming it on that.i finally talked to a real good gm electrical tech i know and he said to have my dealer check the grounds on the trailblazer all of them they found bad ground wires on the left side frame under the driver they replaced the ends cleaned the frame and the problems gone also note my tech said they also seen problems with the grounds under the center console in the trailblazer

hope this fixs your problem P.S. THE GROUND PROBLEM DOES NOT SHOW UP ON THE DIAGNOSTIC COMPUTER THAT THEY USE DEALER KEPT USING THAT OVER THE YEARS AND KEPT TELLING ME WE CANT FIND THE PROBLEM (SO MUCH FOR COMPUTERS)

Whenever I drive at night the lights flicker and sometimes go out completely when I brake or allow the truck to coast. When I use the gas the problem resolves but since I have to stop sometime this isn't a good fix. The electrical guage on my dash fluctuates with the lights going from low to high and back again. I've taken into 2 dealerships but they "can't dupilcate the problem" I work nights so I am driving mostly during the night. How is it save for a young woman to drive alone at night without lights? This problem has happened since I purchased the truck and has not been resolved.