lanching123

Hey all, i recent purchased a 2011 mercedes glk350 and love it. Since I purchased it there has been one issue. The driver side side marker light in the rear does not light up. I was made aware of this via the on dash notification. I figured no big deal, probably a bulb. However, the bulb is not burned out. I confirmed this by trying it in the other sockets and the passenger side. So i figured it must be the bulb socket assembly. To test this i swapped left and right sockets and when i plug the passenger side socket into the driver side it lights right up, no matter which bulb i try. Also, when the driver socket is plugged into the passenger side, no go, it does not light. I thought for sure this would confirm a new driver side socket is needed. I ordered one and sure enough, when it arrived, i had the same exact issue. Even with the new driver side socket it does not light the side marker bulb (and i tried several) on either driver or or passenger side. Now im at a loss. What should my next step be? Is it possible both the old and new socket was bad and i just need to try another one? Please send your suggestions my way. Merry Christmas!

i forgot to mention in all cases the rear fog light, which is the high beam of the bulb in questions, does indeed work. very odd.

dieseldoc

Possibly bad wire or connector.

lanching123

but if it was a bad wire or connector dont you think the bulb would also no light when i switched over the passenger side assembly? Based on what i have done so far, all signs point to a bad socket assembly, but then the new one had the same issue. I have no idea now

lanching123

guys, i goofed haha. After 3 attempts of fixing this and scratching my head, i found what the issue was. I made a stupid oversight but figured i would share to helps those like me. Apparently, the large, lower rear tail light bulb, the one that also serves as the rear fog light, is tied into the little tiny SIDE light bulb to the outside of the vehicle. That was the one my dash was telling me to check, but all i noticed was a non-working lower rear tail light. I assumed that was the issue. Turns out when the little tiny bulb that is actually the side marker goes out, so does the lower rear tail light. I swapped all of the bulbs from one side to the other to discover this. I hope this helps some like me!

delcroix

I was ready to take mine to the dealer until I saw your post. You da' man!!

h3yt8tzmailexus

thanks for the tip lanching123! I immediately changed the side marker bulb after noticing that my tail light bulb was not fixed when I replaced the bulb.

NYCGLK

to add to this...10.5 year car here, what I encountered is the connector metal in the socket flakes and create a contact issue. It seems there are a few micro layers on the contact part that touches bottom of the bulb and when top conductive layer flakes away the next purplish layer doesn't conduct electricity. If you scrape that away you get to the metal part and it works again. The symptom is intermittent non functioning bulb.