Troubleshooting Brake Controller that Flashes When Connected to Trailer

Published 07/29/2015

Products Featured in This Question

Curt Discovery NEXT Trailer Brake Controller - Up to 4 Axles - Time Delayed

(56)

$108.95

Hook Probe Circuit Tester

(60)

$12.27

Question:

Curt discovery brake controller C84VV 2009 Nissan frontier I used the existing wiring connectors on my truck to install the brake controller and the trailer connector. When I apply the brakes without the trailer I get a decimal point on the brake controller as I would expect. With the trailer connected the display on the brake controller flashes. As I adjust the output control it flashes between 0.0 and the 2.0 that I am trying to set the unit at for initial adjustment. It also flashes when I try to adjust the manual control as well. The flashing is very erractic and it is very difficult to try to setup the unit. In looking at the videos the display seem very stable compared to what I am seeing. My camper is a single axis pop up with electric brakes. If I ohm between the blue brake wire and the common I get 2.0 ohms.

asked by: Jeff C

Expert Reply:

It sounds like the problem is corrosion on the trailer 7-way brake output circuit which is causing the controller to only show an intermittent connection. Try cleaning off this pin on the 7-way with some fine grit sandpaper.

Testing the brake controller is fairly easy. 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