Trailer Brake Controller Manual Override Not Functioning but Trailer Brakes Work from Brake Pedal

Question:

2017 freightliner, trailer brakes work when pushing brake pedal, but not when applied manually at controller in cab. Hayes energize III control.

asked by: KEVIN L

Expert Reply:

Since the trailer brakes are working when you press on the brake pedal, it sounds like there could be one of two things going on here. It could be something as simple as the connections inside the controller being dirty or dusty. Give the manual override button a series of pushes and let the button snap back up into place- we just want to try to dislodge anything that might be keeping the button from making a full connection to the internal parts that operate the manual override.

If the controller's manual override is still not working, just to be safe, I'd recommend testing the wiring to make sure that there aren't any damaged wires. I think this is highly unlikely, but it's worth checking out before getting a whole new brake controller-which would be the last option.

inspect the trailer connectors on the vehicle and the trailer for any signs of corrosion or rust and clean as needed . Make sure there are no damaged wires for the connector and the trailer wiring is good as well.

Then, you will need a circuit tester like part # PTW2993 and with the trailer unhooked have someone go through the functions while you test the trailer connector pins. If everything checks out then plug the trailer in and check the wires at the back of the trailer connector on the trailer side to make sure you are showing current.

If the wiring and connectors are all in good working condition then it sounds like the brake controller needs to be replaced. If you do need to go that route, the Tekonsha Primus IQ # TK90160 is one of the most popular models we offer. It will control up to 3 axles with proportional braking and will automatically level itself so that it can detect braking when installed on an angle under your dash.

expert reply by: Erik B