Question Was Asked By - Terry

Flashing Trailer Lights with a 2008 Mercedes GL450 with Factory Tow Package

Question:

I have a 2008 Mercedes GL450 with a factory installed tow package. When I hook up my american hauler trailer and turn on the lights all the lights on the trailer flash on and off, but when I step on the brake pedal they stop flashing and stay lit coanstantly. Both the trailer and the car have seven pin connectors. The trailer has been checked by a local trailer repair facility and there are no problems with the trailer. The lights worked fine when I had my ford f-250.

asked by: Terry

Expert Reply:

It sounds as if you have the trailer ruled out as the problem. I would recommend you check the ground connection on the trailer, to make sure it is connected securely to clean metal, so you eliminate that as a potential problem. I would then look at the connector on the vehicle. Try using a tester, part # TR20117 to check if all circuits are functioning. If you find a problem at the connector, since the tow package is factory, not aftermarket, I would recommend you check with your Mercedes dealer.

expert reply by: Mike

Question:

The local Mercedes dealer, myself and countless others figured out the problem with the flashing trailer lights.Since the trailer is fitted out with l.e.d. lights it seems there was not enough resistance for the cars computer system to register a draw on the electrical system for the trailer lighting system on the car .The solution to the problem was to use a short extension to the trailer wire. It hooks into the cars 7 pin plug and the trailer hooks into the extension. Tried the lights last evening and they seemed to function normally.

asked by: Terry

Have a question for the experts, click here.