Chevrolet Repair Questions? Ask a Chevy Mechanic for Answers ASAP
Double check that the correct bulbs are installed in the brake light. Should be a double filament bulb. If bulbs are correct, try swapping left and right bulbs to see if problem switches sides. If it does, bulb is bad. If it does not then there is a problem in the ground circuit for the left side. You can try attaching a new wire from a good ground to the black wire at the bulb socket. If this fixes the problem, permanently install a new ground wire. If this does not fix the problem then the bulb socket is bad and will need to be replaced.