Constant Voltage on the Break Controller Output Circuit on a 2001 Chevrolet Silverado

Question:

The electric break controller in my 01 silverado is putting 4vdc constantly and up to 11vdc when the breaks are applied. I am having trouble getting my breaks to hold. After checking the voltage I am wondering constantly staying engaged which is wearing the shoes down rather than just not engaging to start with? Should the break controller be putting out the constant 4 volts or should it only be energized when the breaks are in use?

asked by: Daniel

Expert Reply:

The Pilot brake controller that you referenced, # 80550, is a time delayed brake controller and should not show any power on the blue output circuit when the brakes are not applied or the manual slide is not activated.

I like to start with the easiest possibilities first, so try applying the manual slide knob fully several times, letting it snap back to off each time. Sometimes the contact point inside the controller gets dirt or debris in it causing power to be applied constantly or no power at all. Snapping the slide knob back usually cleans the contacts if this is the case.

Next, use the installation instructions for your brake controller, see link, and setup the brake controller from scratch to make sure it is installed and correctly adjusted.

Next, if that does not work, we need to determine why there is power on the output wire. I would check the trailer and vehicle side connectors inside and out for corrosion. Sometimes corrosion will bridge the gap between two circuits and causing a short circuit or bad ground situation. This could be the problem also.

Next, unplug the trailer from the truck. Now, check the brake output circuit in the vehicle side 7-Way, if there is power on the circuit and the brakes and manual slide are not activated, you need to turn your attention back to the brake controller. Sever the blue wire about 6 inches from the controller (so you can reattach it later if need be) then check the blue wire. If there is voltage on this wire without brakes or manual slide activation, there is a short in the brake controller and it will need to be replaced. Brake controllers do not have any internal user serviceable parts.

If there is no power on the brake output circuit on the truck without the trailer attached, check the trailer brake input circuit on the trailer side connector. If there is power on this circuit then the breakaway battery or trailer mounted auxiliary battery is wired incorrectly and that situation will need to be corrected.

expert reply by: Bob G