Trailer Brakes were Working Then Brake Controller Light Turned Red and Says Manual Stuck Failure

Updated 04/26/2025 | Published 02/17/2016

Products Featured in This Question

Dexter Electric Trailer Brake Assembly - 12" - Right Hand - 6,000 lbs

(194)

$87.81

Hook Probe Circuit Tester

(60)

$12.27

Question:

Breaks where working fine then quit the break controller turned red and it now says manual stuck failure

asked by: Randall

Expert Reply:

It sounds like there could be a short somewhere that is drawing constant power and causing the error. The first place I would check is the trailer connector on the tow vehicle then on the trailer. Make sure both are clean and free of corrosion inside, where the wires attach, and outside on the pins. Also inspect the wiring leading to the brake magnets and repair any pinched or damaged wires.

You can also test the brake controller and the brake magnets. In the truck cab you will need to sever the blue wire several inches from the back of the controller. Then use a circuit tester such as # PTW2993 to test the end of the blue wire coming out of the controller. It should only have power when you apply the manual override. If it shows power at idle, then there is something wrong with the controller and it will need to be replaced.

If it tests fine then reconnect the blue wire. You can test the brake output pin and it should only show power with the manual override. If it shows power any other time then there is a short somewhere between the connector and the brake controller you will need to track down.

If the truck side checks out fine then it could be the wiring to the brake magnets or the magnets themselves. Inspect the power wires to the magnets and look for pinched, frayed, or damaged wires and fix as needed. Make sure the ground wires are attached to clean and corrosion free bare metal surfaces.

You can visually inspect the magnets and if you can see the copper windings coming through the magnets will need to be replaced. To further test the magnets you can follow the help article I have linked. I have also included some help articles on testing and troubleshooting brake controllers for you.

expert reply by: Michael H

Terrance M.

4/26/2025

Is it possible that a discharged tear away battery on the trailer is drawing power off the truck and registering this error? Exactly the same thing happened to me, and it’s only a year old controller. Alternatively, condensation in the controller?