Brake Controller Installation in 2016 GMC Acadia

Updated 07/19/2018 | Published 07/18/2018

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Question:

I have installed the T-One Vehicle Wiring Harness for Factory Tow Package - 4-Pole Flat Trailer Connector to my vehicle, the turn signals, break and running lights all work. I have a Tekonsha PowerTrac Electronic Brake Controller, I have connected the Tekonsha Plug-In Wiring Adapter for Electric Brake Controllers - GM under my dash. I can hear a relay clicking when I slide the switch on the controller. Where is the other end of the GMC harness? How do I connect the blue wire going to the trailer to the rear of the vehicle?

asked by: Paul U

Helpful Expert Reply:

Thank you for your purchases and for your photo of the under-dash brake controller connector in your 2016 Acadia.

I checked your order history, and it looks like you initially purchased wiring adapter # 3015-P which does not fit your Acadia. This may have been the cause for the clicking sound since adapters can be pinned out in different ways.

The correct Tekonsha wiring adapter for your Acadia is part # 3026-P. This has a grey vehicle-side plug that matches the design of the one in your photo. This part is intended for the Acadia with the factory tow package.

You can test the black brake controller plug on the adapter once the other end is plugged in to the vehicle by using a tester like # PTW2993. You should be able to detect signals on two of the wires in the black connector (the one that plugs in to the back of the PowerTrac controller). Ground the tester and apply the probe to the contact for the black wire; this wire provides operating power for the controller and should carry +12V without you having to touch anything. The contact for the red wire provides the triggering brake light switch signal to activate the controller; this contact should carry a signal ONLY when you press the brake pedal. These are the signals the controller needs to operate.

If your Acadia does not have a 7-way socket like # 37185 you will need one in order to complete the installation of the brake controller and its output circuit which runs on the blue wire.
Since you already have a 4-pole kit installed to provide lighting signals if you do not have a 7-way I suggest the # 37185 since it will plug right in to the 4-pole you have now. It also provides pigtail leads for making other circuit connections like that for the trailer brake controller and 12V trailer power, as shown in the linked photo.

If you can find a rectangular connector under the vehicle on the frame rail, you can instead use kit # 118271. This connector is shown in the other linked photo. A 7-way is included with this kit, along with fuses and relays. This kit is intended for vehicles with a factory tow package, and it will provide all lighting, 12V power and brake power signals for the trailer.