Issues Finding Stop Light Switch Wire for Trailer Brake Controller Install On Mercedes-Benz GLK

Published 02/17/2022

Question:

Hello, I was at an RV shop because my hitch control unit would be humming loudly, every time I step on the brakes, the humming would stop for a moment. And in addition the fuse for the hitch control would blow regularly. They put in a new hitch plug and a new controller. Running lights work, blinker work but the brake light wire has a CONSTANT 3 Volt charge, so the moment the brake light wire is connected to the control unit, ALL lights are on. It seems like it is a problem with the car wiring. Any idea what is happening and how to fix it? Thank you

asked by: Caroline B

Helpful Expert Reply:

The brake wire you need to hook up to can only have power while the pedal is depressed in order for the controller to work properly. There are several wires coming from the brake pedal and more than one have power. so you just need to be sure you find the cold wire. If you want to avoid this entirely which is what I recommend for most vehicles you can just use the Curt Echo Mobile Trailer Brake Controller part # C51180 which doesn't require any sort of brake pedal connection to function, just 12 volt power.

expert reply by: Conner L