Troubleshooting Trailer Taillight Converter Installation on 2010 Mercedes-Bens GLK

Question:

Hi, I am currently installing the CURT 56200 converter on my 2010 Mercedes GLK. I used the manufacturer wiring diagram and my tester to determine correct wiring. Turn signals work well but my brake light signal is always ON. On the driver side, PINK wire seem to be the correct one but the output of the converter is always at 12-14V no matter if the brake is depressed or not. Could you point me what I could be doing wrong ? Thanks and regards

asked by: Jean-Michel B

Expert Reply:

Newer European vehicles use pretty sophisticated wiring systems that require following the installation steps to the letter. For starters, make sure the vehicle is off and the keys are out of the ignition. Then, connect the white ground wire on the Converter to a clean bare metal surface. Once that is complete, you can connect the black wire on the converter to the positive battery terminal. Make sure the fuse isn't inserted when making the attachment to the positive battery terminal, you'll install that last.

Now make the rest of the wiring connections for stop/tail lights, left, and right turn signals. It's possible that there will be more than one wire that carries stop/tail light signals, so it may be worth checking the remaining wires to be sure. Once all the connections are made, install the fuse. We have found that if these instructions are not followed exactly there will be problems like what you've described. I have included a link to the installation details for reference, as well as to some FAQ articles that I hope you'll find helpful.

expert reply by: Mike L