I am scratching my head on this one. All help is appreciated.


I have a 2005 Mercedes C320 4Matic, put a tow hitch on a few months back and then worked on the wiring. Got a 10amp powered tail light converter MME 35005.


The lights work as expected when the car is NOT running, and the key turned to just before the starter engages. Once the car is running the trailer lights go off. With the car running and lights on, when I press the brakes all the trailer lights go on.
The turn signals lights work as expected when blinkers are turned on.


The MME 35005 has power direct from the battery with a 10amp fuse. The ground is off the body. The trailer seems to be ground properly.
All and any help is appreciated.
Chris