Quote Originally Posted by ozdi View Post
Check the fuse for power supply to the trailer brake controller. Then check if the trailer-brake controller receive the "braking" signal from the trailer controller module J345. Then check the trailer socket.
The problem was an 'on/off' type. Sometimes brakes worked, sometimes not.
At the end of the day I found a shaved wire, assume sometimes shorted to ground.
No blown fuses (so short not bad enough to blow fuse, or tell the controller SHORT).