Troubleshooting Brake Controller of 2018 GMC Adacia Not Working with Brake Pedal

Updated 09/03/2020 | Published 04/20/2018

Question:

So guys at my shop installed break controller. Everything works including emergency 12 volt breaks. But the actual brake pedal sends no signal to trailer breaks

asked by: Andrew H

Expert Reply:

So the red wire of your brake controller needs to be connected to a circuit of your 2018 GMC Acadia that sees voltage only when the brakes are applied. If you used a custom install harness on your Acadia like the # 3026-P to install the controller then most likely you have a blown third brake light fuse since that's connected to the stoplight circuit for the brake controller.

If the controller was hardwired to a stoplight circuit you most likely need to check the condition of the connection the controller is making to the third brake light circuit as it may not be making a solid connection.

expert reply by: Jameson C

Steve

7/20/2020

We have a 2019 Acadia with the trailing package. The four blunt cut wires were found under the dash with no problem. Question, there is no power from the brake signal wire when the brake pedal is applied? Is there something that needs to be activated on the car? I have noticed several others ask the same question. Your input would be appreciated!

Chris R.

7/24/2020

This is a bit strange - I've not really heard of this issue before on the Acadia. There's nothing on the vehicle that needs to be "activated" to get this circuit running. I'm wondering if the brake switch on the vehicle is bad and needs to be replaced? Have you checked with a local GM dealer to see if they have any info?

Steve

7/24/2020

@ChrisR Problem found by the dealer. We have the trailer package from the factory, seven pin plug, prewired. What we didn’t have was the V92 max trailering package. The brake signal wire is purposely “dead” from the factory. If, you don’t have V92, the maximum pull limit is 1000 lbs. We are in discussions now with the dealer.