2026 sierra bad brake controller

[flattop]

Hello, my 3 month old Sierra Elevation wont recognize a trailer with electric brakes? All the lights work correctly, but no power to the brakes?

 

This is the factory installed brake controller. If you manually push the knob, the display shows the power % but does not light up like my 2022 silverado.

 

I have an appointment with the dealer, but was checking to see if anyone else has seen this issue. 

 

Thanks, 

[asilverblazer]

Older trucks had to have a fuse and wire connected underhood... You could check that. 

 

I've noticed a lot of aftermarket discrepancies between wire standard colors/plug terminal location function. If you've never used the trailer on a GM truck it might be something to check.

[newdude]

21 hours ago, flattop said:

Hello, my 3 month old Sierra Elevation wont recognize a trailer with electric brakes? All the lights work correctly, but no power to the brakes?

 

This is the factory installed brake controller. If you manually push the knob, the display shows the power % but does not light up like my 2022 silverado.

 

I have an appointment with the dealer, but was checking to see if anyone else has seen this issue. 

 

Thanks, 

 

 

Sounds like the trailer brake power module failed.  Common on these.  

[flattop]

I had asked the tech when I scheduled the appointment about adding the 40 amp fuse like the old days, he said he did not know and they need to see the truck! He acted like this has never happened before and was not a common failure?

[newdude]

10 minutes ago, flattop said:

I had asked the tech when I scheduled the appointment about adding the 40 amp fuse like the old days, he said he did not know and they need to see the truck! He acted like this has never happened before and was not a common failure?

 

 

I see them do them all the time at work.  Fuse won't fix a bad module.  

 

They recalled the power modules on the HDs for them failing on 2020-2024 HDs but they use the exact same module.  We've done some 2024-2026 1/2 tons already that needed a new power module.  

 

Other possibility is corroded wiring.  There's a spot the chassis harness runs to the back along the frame rail.  We had a 2025 that had a bad section of wire there but I think it was for a different issue.  

Edited 14 hours ago by newdude