Why Would Trailer Brake Controller Circuit Always have Pulsing Signal On Circuit

Published 05/24/2016

Question:

With the trailer disconnected from the vehicle I put a test light between the blue wire and ground and I see a dim pulsing light. I see the same thing whether or not the brakes are being applied from inside the cab? Is this normal? When I hook the truck up to my newer RV everything works correctly? When I hook up to my car-hauler trailer it doesnt work correctly? So I know I have an issue with the brakes on my car hauler. Therefore I am assuming the pulsing dim light is normal. Maybe my test light doesnt put enough of a load on the controller to activate it? Ideas?

asked by: Owen H

Helpful Expert Reply:

The pulsing you are seeing on the brake controller output circuit is normal. That is the controller testing the circuit to see if it detects the load of trailer brake magnets. If it detects the magnets it will show that the controller is connected. If it doesn't sense anything the controller shows that it is not connected to a controller.

The problem has to be on the car hauler trailer. First thing to check is for corrosion on the trailer connector as that typically is what prevents brakes from working. Especially if the controller does not read that a trailer is connected when the trailer is.

I attached a help article that details troubleshooting brake controllers for you to check out as well.

expert reply by: Jameson C