Troubleshooting Curt Spectrum Brake Controller that Shows 3.4 Volts on Output at All Times

Updated 09/24/2019 | Published 09/23/2019

Products Featured in This Question

Curt Spectrum Trailer Brake Controller - Dash Mounted Knob - Up to 4 Axles - Proportional

(410)

$259.95

Hook Probe Circuit Tester

(60)

$12.27

Question:

Ive hooked up the spectrum controller to my 2010 f150 and I get 12v when applying the brake into the controller. But for some reason it sends a constant 3.4v out to the 7pin. Brake pressed or not. I have running lights but no brake lights working..

asked by: Ray A

Expert Reply:

If you are getting a constant 3.4 volts on the brake output circuit of your brake controller without the brake pedal pressed that's a malfunction of the brake controller. Curt controllers are known to be a bit more prone to internal bugs so the first thing I would try is to unplug the controller for a few seconds to see if a hard reset fixes the issue. Here's how to test a brake controller completely to determine where the problem is:

Testing the brake controller is fairly easy. Sever the blue brake output wire near the brake controller leaving enough room to reconnect it and then apply the manual slide. Using a circuit tester like the Quickee Tester, part # PTW2993, you should get output to the controller side of the wire you severed. If the manual slide activates the trailer brake output wire properly, try the brake pedal. If the brake pedal activates the brake output properly also then the problem is farther back either in the vehicle wiring or on the trailer.

If either the brake pedal or the manual slide are not functioning properly you will need to test the wires going into the brake controller. Make sure you have power entering the brake controller on the black wire. On the red wire you will only want power when the brake pedal is pressed.

If there is power on the red wire before the brake pedal is pressed you have connected the red wire from the brake controller to the wrong circuit. You would then need to find the brake switch wire that has power ONLY when the brake pedal is activated.

If these connections check out and the brake controller is properly grounded then there is possibly a problem inside the brake controller.

I am including a link to a video that will show you how to test the wiring on a brake controller.

expert reply by: Jameson C