The complant is that its only locking the brakes up on one side of the trailer, that sounds like a trailer issue but he is convinced that its a truck issue, it almost sounds like seals could be out on the trailer, just put the tester on the truck and start there and Dignose the issue and we will  contact coustomer with Quote 

Brake Contoller is not working, he wants to go  aftermarket becouse he keeps having to fix it.