Service Trailer Brake System

[Recycledoug]

I have a 2017 GMC Sierra 1500. After about 6 months of ownership the service Trailer Brake system light came on... I have since taken the truck back to my servicing dealer over 5 times to resolve the issue. The last time the truck was in the shop, they ended up bypassing part of the "harness" with a wire in order to skirt the possible short in the system... The good news is that this seemed to fix the problem... However, after the truck sat for two weeks (in pouring Cincinnati rain) the light came back on... And my trailer brakes for sure are not getting activated. The dealer worked on it for a day (again) and has not come up with a solution... The truck goes in again next week.... Not good...

My guess is that a complete new harness from the control module under the dash to the rear relay is what is needed....

Has anyone else had this issue... It has been a real bummer for me not to be able to tow my trailer for the last 4- 5 months.....

 

[Recycledoug]

I have a 2017 GMC Sierra 1500. After about 6 months of ownership the service Trailer Brake system light came on... I have since taken the truck back to my servicing dealer over 5 times to resolve the issue. The last time the truck was in the shop, they ended up bypassing part of the "harness" with a wire in order to skirt the possible short in the system... The good news is that this seemed to fix the problem... However, after the truck sat for two weeks (in pouring Cincinnati rain) the light came back on... And my trailer brakes for sure are not getting activated. The dealer worked on it for a day (again) and has not come up with a solution... The truck goes in again next week.... Not good...

My guess is that a complete new harness from the control module under the dash to the rear relay is what is needed....

Has anyone else had this issue... It has been a real bummer for me not to be able to tow my trailer for the last 4- 5 months.....

On 3/2/18 my dealer ended up pigtailing the wires to the rear trailer electrical relay and shrink sealing the connections. All is well for now. Hopefully this issue is fixed for good....

 

[redenbacher]

Thanks for your info. I have the same issue and was searching for a solution when I found this. My dealer says "it's the trailer" but I had the trailer checked stem to stern with no issues. I'm going to copy your info and work with dealer. The funniest is when I had no trailer attached and got a "service trailer brake system" warning on dash.

 

[G-831978]

Did you ever figure it out? I have the same issue with the service brake system flashing on the dash without a trailer hooked up. I have changed the module out and checked all wiring and still can't find a solution.