How to Power Brakes and Troubleshooting Trailer Lights on a 2012 Mercedes Benz GL 350

Question:

I have a GL 350 2012 mercedes with factory tow package Im new to this stuff. 1. The trailer lights and signals did not work correctly, I see that I may need the 7-way adapter. 2. Should this control the brakes on my trailer. 2006 airstream bambi. I cant seem to tell if its working, but I dont hear anything when I engage the parking break.

asked by: Sunny T

Expert Reply:

With a 2012 Mercedes Benz GL 350 the adapter # 20142 should take care of your lighting issue if the problem is with the lamp-out sensor. If you had a different issue let me know what you're experiencing so we can troubleshoot.

To power the brakes on your Airstream trailer you'll need an electric trailer brake controller. This is a device that usually installs in the vehicle's cab and is connected to the stop light switch coming from the vehicle's brake pedal. When you apply the brakes in your Mercedes it will send a signal through the 7-way trailer connector to engage the trailer's brakes.

With your vehicle I recommend using the Curt Echo # C51180 for a brake controller. This way you don't have to splice into the wiring of the Mercedes. The Echo installs in the 7-way and uses the 12 volt circuit from the vehicle. Then it communicates with a smartphone, wirelessly, that you keep in the cab of the Mercedes. I verified with the manufacturer that the brake controller will work with the adapter plugged into the vehicle's 7-way.

I've linked a video on the Echo for you. As well as an article on electric brake controllers.

expert reply by: Charles S