Brake Controller voltage output

hillrider · June 25, 2015

Having a issue with weak brakes on my TT. Can't tell if it's the truck or the camper. Has anyone seen what the output voltage should be on the brake wire with full controller bias? (This is a GM factory controller). Looking for some guidance as to which end to start with. Truck or Camper.

shooter468 · August 11, 2015

At max output you should have 12v. Check with a colt meter at the plug with someone gradually increasing the gain.

If that checks out check the adjustment of your trailer brake shoes. If the adjusters ( which are like most any other drum brake setup) are hard to turn or frozen , remove the drums. This will give you access to inspect the brake components, shoes, magnets, & the surface of the drum that the magnet rides on. It must be as flat & groove free as possible for maximum contact. Shoe surface is the same. Also make sure it's clean & dry in there. Good luck.

ember1205 · August 15, 2015

I've actually been told that the factory controller puts out 10.5V and -not- 12V. Might be worth a call to the service department or check with a GM tech on here that has the information.

As far as brake adjustment goes - definitely make sure things are in good order there. If you happen to have the Dexter No-Adjust axles, there should be no need to adjust the brakes unless they're significantly worn (and that's definitely another item to check for when you have it all apart).

If your brakes ARE very worn, you'll likely have to run a higher gain on the controller.

14GFXSilverado · August 15, 2015

Yes the controller wont actually put out a max power of 12v to the trailer. With my shop we have tested this is many trucks... dodge and ford are the same way. I was told by a chev tech in town here that said they do that to prevent people from completely locking the brakes and possibly causing someone to lose control.

I don't completely agree with it but thats what I have been told and have seen on many trucks.

As far as the brakes do check them out and make sure the adjustment is good on manually adjusted brakes. Like shooter said make sure the touching surfaces are not completely grooved or wore down. Also check the magnet arm and make sure the that the magnet and arm move freely and spring back to center location after releasing. Having possibly ceased arms could cause lack of brakes as well.