Adding a 7-Way and Brake Controller to a 2012 GMC Terrain and Old Trailer

Updated 08/18/2014 | Published 08/17/2014

Products Featured in This Question

Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat - 10 Gauge Wires

(3478)

$118.67

Pollak Black Plastic, 7-Pole, RV-Style Trailer Connector - Trailer End

(724)

$7.62

Question:

HI, I have a 2012 GMC Terrain with a standard 4 pin connector. I have an antique trailer with 4 PIn connector all working fine with the truck. The trailer has electric brakes that have been disconnected. Is there an adaptor that I can buy that allows the + wire on the brakes to be energized when driving? As far as I can tell, the brake light on my 4 pin overlaps with the turn signal, which would turn the brakes on everytime I used the blinker? Thanks!!!

asked by: JOhn

Expert Reply:

Trailers have combined turn signals and brake lights on the same circuit so you wouldn't tap into one of those otherwise the brakes would turn on with the blinker like you said.

You are going to have to add a 7-Way connector to the 2012 GMC Terrain and to the trailer. And you will also need a brake controller.

Since your Terrain already has a 4-Way you will just need # ETBC7 to add the 7-Way. I have included some links that show and explain the ETBC7 installation as well as the brake controller installation. For a brake controller I recommend the P2 # 90885. It is our most popular controller because it is easy to set up and use and it is reliable.

For the trailer side you will need # PK12706. When you open up the 7-Way to attach the wires each pin location will be labeled so you know which wire goes to which pin. You cannot go by color since there is no standard. I have also included a diagram that shows how a trailer side 7-Way is wired. Ignore the colors and focus on the functions.

expert reply by: Michael H