Reader Question I have a 2001 Saturn LW200 wagon. During the day, if I hit the brakes, the taillight will work normally — it displays Red. However, if the headlights are on, and you hit the brake, the driver’s side taillight no longer works. I swapped out the bulb, but this does not solve the issue. Is this a problem with the taillight assembly, wiring, or something else?
That is usually a “ground” issue of some kind. A pinched, broken, or corroded wire or bad socket connection can cause that. You swapped the bulb, but I would swap all bulbs in the rear and make sure all sockets fit the bulb good and tight. I would also check the driver’s front park light bulb as well, and swap it for the passenger front just to rule out the possibility of a problem in the front socket.
If you still have problems, you will probably need to see the mechanic and have them test the sockets and grounds but try to rule out the possibility of a faulty bulb or bad connection first.