Should there Be Power on the Blue Wire on a Brake Controller without the Brake Pedal Pressed

Question:

2001 silerado..when testing install..I hooked a test light to blue output wire from controller..I noticed green LED illuminated and barely lit test light. test light gets brighter when brakes are depressed. My question is.. should there be power on the blue output wire when brakes are not depressed and test light is hooked up?? There is definately power there..not alot..but some

asked by: Mike B

Expert Reply:

The way that a brake controller determines if a trailer is connected is by sending a small amount of power back on the blue wire. This is normal and it sounds like your controller is working properly. If there was a lot of power, more than a few volts or more, that could indicate a problem with the controller. I have included a link to troubleshooting trailer brake controller installations that might help should there be any issues. If you connect the trailer and the brakes are NOT engaging then you know that the power going through the blue wire is just a sensing voltage to determine if a trailer is connected.

expert reply by: Michael H