Hardwiring Brake Controller to 2017 GMC Acadia Troubleshooting White and Blue Wire Not Active

Question:

Hi Jameson you sent me an email about the third brake light not working to cause the white wire with blue strip not to have a signal to brake controller, but the light is working. Thank you for your input, but I didn,t think I would be that lucky. If you have another idea I would like to hear it. Thank you for all your help

asked by: Joseph B

Helpful Expert Reply:

Does the third brake light of your 2017 GMC Acadia still activate? Normally if the stoplight circuit on a GM vehicle stops working the issue is a blown third brake light fuse. The white wire with the blue stripe on a 2017 Acadia is supposed to be the stoplight circuit. I'd be willing to bet the fuse is just blown.

expert reply by: Jameson C

Joseph B.

10/4/2018

Jameson C.

10/4/2018

You can try testing wires that lead to the brake light switch on the brake pedal till you find one that has voltage only when the brakes are applied. This is how brake controllers have to be wired to vehicles that don't have factory wiring. Or you can use the Roadmaster Universal Stop Light Switch Kit part # RM-751000 which you can install on your vehicle to get a dedicated brake switch. Our installers here use this kit when they aren't able to find a dedicated signal.