bensonchuong

2012 C300
I get a message to check the rear right turn signal. With the hazard switch on, both rear turn signals work fine when the vehicle is stopped, engine not running. But if it start the car then the right side turn signal will stop working. The turn signal is an LED built in so I'm not sure where to start looking.

TimC300

Hazards both work with engine off AND engine running?

Right turn signal does not work with engine off AND engine running?

There might be seperate relays, one for the hazards and another for the turn signal. Im not 100% sure.

I think this may be the correct relay diagram. Think its the one under the hood.

bensonchuong

Hazards and Turn Signal all work with engine OFF.

With Engine ON, Right Rear light doesn't work with Hazard or Turn Signal.

TimC300

I dont know much about electrical, just a little. Can you remove that bulb from the carrier? I looked online at 2012 bulb carriers and im not sure which is the turn signal bulb, assuming its the big led bulb on the top. If you can pull it I would put a multimeter on the connections and check the voltage with the turn signal on with the car off then with the car running. From my quick search on the issue about bulbs on with the car off but they dont work with the car running seems to be a ground issue. Look at the wiring harness where it connects to the tail light, ground might be the brown wire, check for any corrosion or if its loose.

JettaRed

iTrader: (1)

Turn signals and hazard lamps are on different circuits with different fuses. Check fuses 13 and 18. Both are in the engine bay fuse box, driver's side by the firewall.

https://www.mercedesmedic.com/c-clas...ayout-diagram/