Is there a Brake Controller Wiring Harness for a 2008 Mercedes GL550
Question:
How do I order the proper wiring harness for the trailer brake controller so that I can just plug it into my car. I have a factory installed brake controller port under the dash. The controller Im going to order from you is the Curt Triflex Trailer brake controller. Part # C24VV and C51515. My vehicle is a 2008 Mercedes Benz GL550
asked by: Tom B
Expert Reply:
There isn't an aftermarket brake controller wiring harness that will fit your 2008 Mercedes GL550, so you have a couple of options. First you can see if there is an adapter from a Mercedes dealer with one end that plugs into the port under the dash and the other end with just wires. Then you could wire the controller to that adapter harness.
The other option is to determine the functions of the pins in that port using a circuit tester such as # PTW2993 or a meter if you have one. One pin will have power only when the brake pedal is applied, and one will have constant power.
The ground pin and brake output pin are a little more difficult to determine. If you can run 12-volt power backwards (from the pin in the 5 o'clock position on a 7-Way trailer connector) then one of the pins will show power when it didn't before. That would be the brake output pin. The remaining pin would be the ground.
Brake controller wire functions are:
White = ground
Black is 12-volt power into controller
Red is input from the brake switch (power only when brake pedal is pressed)
Blue is output to the trailer brakes
Products Referenced in This Question
Product Page this Question was Asked From
Curt TriFlex NEXT Trailer Brake Controller - 1 to 4 Axles - Proportional
- Trailer Brake Controller
- Proportional Controller
- Electric
- Electric over Hydraulic
- Automatic Leveling
- Under-Dash Box
- Dash Mount
- Up to 4 Axles
- LCD Display
- Up to 360 Degrees
- CURT
more information >
Featured Help Information
Instructions
Miscellaneous Media
Continue Researching
- Q&A: How Does Curt TriFlex NEXT Brake Controller Mount
- Article: Brake Controller 7- and 4-Way Installation Kit (ETBC7)
- Article: Trailer Wiring Diagrams
- Q&A: Which Blue Ox Weight Weight Distribution System for Lance 1475 Trailer
- Q&A: Recommended Plug and Play Adapter for a Curt Brake Controller on a 2019 Ram 1500
- Q&A: Selecting The Correct Weight Distribution Hitch For a 2024 Keystone Hideout Sport 175BH
- Q&A: Should I Get a Proportional or Time-Delayed Brake Controller
- Q&A: Parts Needed To Install a Trailer Brake Controller On a 2024 Hyundai Santa Cruz With Factory 7-Way
- Article: Towing a Trailer? Let's Talk About Brake Controllers
- Article: Brake Controller Installation: Starting from Scratch
- Q&A: Recommended Brake Controller For A 2024 Chevy Silverado 1500
- Article: 5 Things to Know About Weight Distribution Hitches
- Article: How to Measure for Trailer Hitch Drop
- Article: How to Choose the Right Trailer Hitch Class