All of our rear lights are part of a "Grid". Meaning they all run on the same (exposed) metal circuit board (for lack of better term). If there is a problem with one light bulb, it can easily affect other bulbs. I suggest taking all of the bulbs out, checking to make sure they are all working (by looking at the filament) and then putting them back, one by one, making sure you're using the correct bulbs (and correct wattage) in the correct socket. Lastly, make sure the wire harness is in correctly (and nice and tight).

If that doesn't work, then you have a real issue to worry about.

G/L

 

I had an issue with my turn signals (not the same as yours) but I replaced the Hazard Switch and that fixed the problem. They are connected as the turn signal relay is located within the switch. I don't know the year of your car but I am sure there is a video or details on how to remove the trim without cracking it. Then removal of the switch is easy. Mine had 2 screws that I could not see until the radio head unit was slid out. Others are different though.

 

The hazard switch controls the blinking of the Amber lights only. If that switch goes bad, your lights will still work. They just won't blink.

 

Thanks for the clarification. That is why the turn signals were fixed in my case when I replaced the hazard switch because they are tied together.. but I did not have any other issues. Wasn't sure if other issues could also be tied together given his turn signals were also not working properly. Did not mean to lead anyone astray.

 

Well, any legit information is good information when you're trying to diagnose something. It's always possible that he could have co-occurring issues. One of which could in fact be the Hazard switch. Worst case scenario, he now knows about the hazard switch, so when it goes out (and it will eventually), he'll know what it is.