Troubleshooting Brake Controller that Intermittently Activates Brake Actuator

Question:

I have a big Tex 40’ trailer with disk brakes with hydraulic fluid in the front of trailer. The manifold on the trailer keeps activating when plugged in like it thinks I’m putting on brakes but I’m not. I just got the brakes replaced and had all wiring checked on trailer and truck thinking it might be the controller in the truck. Not the issue any suggestions? Thank you

asked by: Kyle S

Helpful Expert Reply:

When the trailer brakes randomly lock up does the brake controller show anything on it's display? It's pretty easy to test the controller though.

Sever the blue brake output wire near the brake controller leaving enough room to reconnect it and then apply the manual slide. Using a circuit tester like part # PTW2993, you should get output to the controller side of the wire you severed. If the manual slide activates the trailer brake output wire properly, try the brake pedal. If the brake pedal activates the brake output properly also then the problem is farther back either in the vehicle wiring or on the trailer.

If either the brake pedal or the manual slide are not functioning properly you will need to test the wires going into the brake controller. Make sure you have power entering the brake controller on the black wire. On the red wire you will only want power when the brake pedal is pressed.

If there is power on the red wire before the brake pedal is pressed you have connected the red wire from the brake controller to the wrong circuit. You would then need to find the brake switch wire that has power ONLY when the brake pedal is activated.

If these connections check out and the brake controller is properly grounded then there is possibly a problem inside the brake controller.

I am including a link to a video that will show you how to test the wiring on a brake controller.

expert reply by: Jameson C