Trailer Brake Controller Shows 12 volts on Blue Wire All of the Time

Question:

Reno: I checked the red wire at the brake light switch, all good. I checked voltage at black wire, battery voltage. I then separated the wire going to the 7 way coming from the blue wire and read voltage directly at the controller. I am still getting a reading of 12.26 on the blue wire at the controller. I tried snapping the manual lever, with no result. The controller was still working when last used but just experiencing the battery drain when not in use. Is it time to invest in a new controller?

asked by: Shawn

Expert Reply:

Based on what you have said here the brake controller is faulty and it will need to be replaced. There should not be power output on the blue wire behind the controller all the time. This indicates a problem with the internal circuitry of the brake controller but there are no user-serviceable parts inside so you will need a new one.

I recommend the Tekonsha P2, # 90885. This is a proportional brake controller and one of our top sellers because it is easy to set up and use. I have included a link to the installation details for you. The wiring will be the same: white is ground, black for 12 volt power, blue is output to the trailer brakes, and red is input from the brake switch. It may be time for some fresh connections as well to make sure everything is working properly.

expert reply by: Michael H