When I step on the brake, the trailer brakes don't apply.......the light on the controller turns on, but the brakes on the trailer won't apply. When I apply the trailer brakes manually with the slide, they work fine. Any ideas?

 

check the pendulem switch to make sure its balanced right

 

I didn't know it had one........how would I check that?
The controller brand is Kelsey(never heard of them, came with the truck).

 

Should be a little lever on the side of the controller.

 

Toss it and go buy a Prodigy or a P3. Set it and forget it.

 

buy a brake smart its the best you can get .theres no replacing safety!
or next a podigy-or P3 these are the top 3 controllers hands down

 

That's what it was........Thanks!