Troubleshooting Error Code PL from Tekonsha Primus IQ Trailer Brake Controller TK90160

Question:

Hello I have 2002 chevy 2500hd and I have primus iq installed today I wired everything in and the controller had the error Pl and the trailer brakes worked and they would not up until I had this error and the the brake lights wouldnt shut off on the truck. I had to cut the brake Petal wire on the controller to get them off. Why would this be?

asked by: Erik

Expert Reply:

On the Tekonsha Primus IQ Trailer Brake Controller # TK90160 the error code PL indicates that the 12V power feed to the controller was interrupted while the pedal was pressed. The controller's black wire carries this 12V input power from the vehicle battery. In a truck with a factory 7-way this connection is part of the quick-connect adapter that is available, part # 3025-P.

It sounds like either the controller has gone bad or that there is a short somewhere in the wiring on the truck or trailer that is allowing power to back-feed into the Primus. This would explain your brake lights staying on. You can apply a tester like # PTW2993 to the red wire to see if the unit is sending power through the red wire. Do this without pressing the brake or manual override. If you detect a signal on the red wire when you're not pressing the brake or the override then this tells us the controller is damaged and should be replaced.

You can also test the blue wire, the controller's output circuit, again without pressing the brake or override, to see if a short in either the vehicle or trailer connector is allowing the 12V circuit to short to the brake circuit. This too could allow 12V power to reach the controller through the blue output circuit wire and cause your brake lights to illuminate.

expert reply by: Adam R