2007.5 2500HD Trailer Brakes

[Nate Carlson]

2007.5 2500hd OEM trailer brakes are not working correctly. A few details:

 

1. It is truck-side. I hooked up a different truck to my trailer, and the brakes worked.

2. I replaced the trailer brake module and the relay located by the back tire and also checked the fuses.

3. The trailer brakes work if I start the truck while holding the brake. Then as long as I continue to press the brake, they work.

4. Once I let go of the brakes for more than 3 seconds, a notification comes on the dash saying "Service Trailer Brake System." If I press the brakes after this point, the trailer brakes do not work.

 

Any help would be appreciated. 

 

Thanks!

Edited November 11, 2021 by Nate Carlson
Giving more info

[davester]

You need to indicate if you have a "classic" '07 (NBS) or the mid-year upgrade 07.5 model (NNBS), as they are pretty different trucks.

 

I dont know enough about the details of how the system works to be able to assist you.  If nobody else does, perhaps sign up for a subscription to the full-service manual for your truck and go through it's braking section.

[Nate Carlson]

Thanks- just fixed the title of the post. 

Edited November 11, 2021 by Nate Carlson

[davester]

...and the fix was?

[Nate Carlson]

I meant that I fixed the title of the post. I didn't fix the problem.

[Formulabruce]

Check the grounds on the brakes. some controllers are more sensitive.

 The grounds are usually a metal magnetic disc that moves and tightens the arms/shoes.

These, and the area they ride on can get rustly