How Do I Test My Tekonsha Primus IQ Brake Controller To Determine If I Have A Short In The Wiring?

Question:

My break control is flash s.h and o.L I am not loaded and I can not find a short any were could my control be bad

asked by: Jay

Expert Reply:

While it is possible that the Tekonsha Primus IQ Trailer Brake Controller # TK90160 could be bad the multiple errors that you are seeing point to wiring issues.

The S.H denotes a short in the brake wire during idle condition. Since you are not connected to the trailer it would seem that the blue wire is shorting to ground. And this would explain why you see the o.L as well as when it attempts to send the power through the blue wire to the trailer it is overloaded since it does not have a solid ground connection.

You can bench test the Primus to determine if it is faulty. You will need to connect the black wire to a positive battery terminal, the blue wire will need to go to a 12 volt light bulb and the ground side of the bulb ran to the negative terminal of the battery. The red wire will not need to be connected for testing yet. Connect the white wire to the ground of the battery and you should be able to operate the manual lever of the controller and will see the bulb light. Be sure that the output is set to max when testing. If the bulb lights you know the manual override works properly. By touching the red wire to the positive terminal of the controller it may not light the bulb due to the inertia sensor on the controller.

expert reply by: Bud M