Mercedes GLC Diesel Turn Signal Problem

That sounds like a proper nuisance. So, you've got the whole light show going on, eh? Error codes flapping about, the dash lighting up like a Christmas tree, and the actual blinker throwing a hissy fit. First things first, did you check the bulb itself? I know it sounds basic, but sometimes it's the simplest things that catch you out. Also, have you had a gander at the flasher relay? Those can be temperamental beasts. And yeah, you mentioned the wiring, which is fair enough, but are we talking chafed wires, corroded connectors, the whole shebang? Give us a bit more detail.

Thank you for your response. I inspected the bulb and it appears functional. Regarding the flasher relay, could you elaborate on the diagnostic procedure for confirming its proper operation? With respect to the wiring, what specific areas are most prone to failure in this model?

Right, the relay. Honestly, without proper diagnostic gear, it's a bit of a guessing game. A multimeter would be your best bet to check for continuity and voltage. But given all the electronic wizardry in modern Mercs, it's often a CAN bus issue throwing a wobbly rather than a dodgy relay. Wiring-wise, check anywhere the loom flexes, especially near the light cluster itself and where it passes through the bodywork. But realistically, with those symptoms and that mileage, and you suspecting a wiring issue, I’d be leaning toward a trip to the dealership. They have the STAR diagnostics system that can pinpoint the fault pronto. Could save you a lot of head scratching and potential further damage. Could be something as simple as a dodgy earth, but chasing that down can be a right pain without the proper tools.

I appreciate the detailed advice. Following your suggestion, I consulted with a qualified technician. The issue was indeed a faulty connector within the turn signal circuit, as initially suspected. The repair, consisting of connector replacement, cost approximately 95€. The turn signal is now functioning correctly.