Curt Triflex Brake Controller Intermittent Error Code Trailer Not Connected

Updated 06/05/2019 | Published 06/04/2019

Question:

I have a 2013 GMC yukon Xl Denali and had a Curt triflex brake controller professionally installed at the GM dealer. I have hooked the RV trailer up to my neighbors truck with a brake controller and it operates just as it should. I hook it up to the Yukon and it works for a minute, then flashes dc, then releases and displays CC before going back to two dots every time I press the brake pedal. Each time all of the RV wheels completely lock up. I checked and cleaned all the connectors in the back, tested for power and everything seems to be fine. I checked the grounds on the trailer again and everything is fine, especially after testing it on the neighbors truck. It leads me to believe its in the Yukon. What else may be causing this?

asked by: Colin D

Expert Reply:

You are correct in your thinking that the problem is not the trailer since the brakes work properly when hooked up to the neighbor's truck. The issue is most likely the ground on the trailer connector on the Yukon or the Curt Triflex itself part # C24VV. It sounds like you have checked your connections and grounds but it is a good idea to make sure the trailer connector on the Yukon is grounded to clean bare metal surface and that the brake controller itself is grounded properly. The brake controller is intermittently not recognizing the trailer is connected since it goes from disconnected to calibrating and then standby mode which could mean the ground is not sufficient enough. You said you have power to the pins on the trailer connector so that is good. I have also been told by Curt that sometimes unplugging the controller and resetting it helps with issues like what you are having.

The next step is too check the wires from the back of the brake controller to make sure they are not loose. I am not sure how long you have been having this issue but the installer may have incorrectly hardwired the red wire to the cold side of the stop light switch. You want to make sure all connections are good there. The last step is too test the blue wire from the back of the brake controller by severing it about 6 inches back from the brake controller and testing it with a circuit tester while you hit the manual override on the Triflex. Also test it while you press the brake pedal. If you have full voltage there (light on circuit tester is bright) then the brake output wire from the brake controller is okay and the issue is with the wiring and I would take it back to the installer (if it's a new install).

If you have no power or intermittent power at the blue wire then the brake controller is defective and probably needs to be replaced.

expert reply by: Heather A