Troubleshooting Brake Controller on 2008 Toyota Tundra  

Question:

Expert Reply:

It sounds like you have the Tekonsha Primus IQ Trailer Brake Controller # TK90160 along with the custom wiring harness # 3040-P on your 2008 Toyota Tundra. If this is the case, then I recommend using a circuit tester like # PTW2993 to test the wires in this installation. First, I recommend testing your wires directly behind your brake controller in the wiring harness. You can either probe the wire insulation or put the point in the plastic harness far enough to read connection. Make sure you have a good bare metal ground on your tester and on your harness and then start with the black 12V power wire. If that is good, then move to the red stop light wire. If the red wire lights up when you hit the brake pedal and does not light up when the pedal isn't pressed then it is working properly. Next check the blue wire when using the manual override on your brake controller. The light in your tester should get brighter as you increase the power by adjusting that slide.

If that checks out, then move to the trailer connector at the bumper. Check the 5 o'clock pin for power when using the manual override on your controller. If it does not work, but did under the dash, then you have a wire short and need to replace the wire. If it does work, then your controller is working properly. It is important to note that a proportional brake controller like this will not show the power from your brake pedal only at the 7-way 5 o'clock pin when tested because you aren't moving and the internal deceleration sensor in the controller is sensing not to send any power because you are already at a stop.

expert reply by: Jason S

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