Sorry for starting a new thread. My front driver side turn signal stopped working. I noticed the socket was bad. I replaced that and the bulb. Still not working. The side mirror signal works. The back works. I’m stumped. Its a 2003 model
Ther should be a connector that mates to the socket. Disconnect it and use a voltmeter to check for continuity. Turn on the signal and see if power goes on and off as the light should.
Don’t be sorry for starting a thread. I’m glad you did. Hopefully, you will solve the problem with our help and you’ll end up happy that you started the thread.
The lighting module should be connected to the car’s wiring harness through a plug setup. Try checking there. They’re normally located along the bottom of the unibody, and they are thus subject to corrosion.
Perhaps if you ask nicely you can con the Mercedes parts guy to show you a copy of the appropriate wiring diagram (NOT the schematic, the one that shows the wire routing). If so, that will show you exactly where the plugin is between the module wiring and the main wiring harness.
There is a “repair kit” for the front turn signals on this model
The problem is a bad ground, if memory serves
The Benz parts department should be able to get one for you. I believe it’s a bulb, socket, and a pigtail. I’m pretty sure it involves removing one wire and placing it in the new pigtail
It’s been several years, but I believe it’s not an overly complicated repair. In any case, if you give the parts gu some krispy kremes, he’ll probably print out the work procedure.
OP could check the resistance between the bulb’s socket case and chassis ground to confirm this is a grounding problem. Should be less than one ohm.