Troubleshooting Brake Controller that Only Says Connected with Circuit Tester on Blue Wire

Published 08/25/2016

Question:

I have power to the controller but the green light is not on. if I put my test light to the blue wire the light comes on. is this a ground problem

asked by: Kevin K

Expert Reply:

What you described is the brake controller not sensing a trailer connecting. Brake controllers are constantly pulsing the blue wire of their wiring looking for a load to detect which indicates a trailer is connected. Since yours only detects a load with a circuit tester on the circuit that indicates that you most likely have a dirty trailer connector that is preventing the connection from being made between the trailer and tow vehicle.

Try cleaning the connector with fine grit sandpaper and ensuring the pins are making contact and the controller should start working again.

expert reply by: Jameson C