Troubleshooting Tekonsha Primus IQ Not Activating Brakes During Trip

Updated 04/02/2019 | Published 04/01/2019

Products Featured in This Question

10 Gauge Wire - Blue Primary - Per Foot

(108)

$1.65

Deka Heat Shrink Butt Connector - 12-10 Gauge - Nylon Insulation - Yellow - Qty 5

(1141)

$7.51

Cordless Circuit Tester

(15)

$19.29

Question:

My Tekonsha Primus IQ Trailer Brake Controller # TK90160 which I bought and installed 6 months ago has been working like a champ, until yesterday. During a trip, while exiting the highway I noticed that I no longer had trailer brakes. Upon further inspection it says NC not connected, when it clearly is. The problem doesn’t appear to be my connector because all of the trailers parking lights are working fine. Any ideas on where to look next?

asked by: Jack M

Expert Reply:

Since your Primus IQ Trailer Brake Controller # TK90160 is on a separate circuit from the rest of your trailer wiring it actually could be your connector. The best way to tell where to start looking though is by using a circuit tester like part # PTW2979 to test the pin in the 5 o'clock position on your vehicle 7-Way (see attached photo). Set the power from the Primus IQ to the highest setting and then have a helper use the manual override to send full power back to that pin. If the tester lights up then you know the problem is on your trailer. If the tester doesn't light up then the problem is on your tow vehicle.

For your vehicle side you need to determine if the problem occurs before or after the Primus IQ. Cut the blue wire about 6" back from the brake controller and try the method mentioned above with the circuit tester to see if it is getting power. If it is then that means there is a wiring break somewhere between where your brake controller installs and the 7-Way on your vehicle. If it isn't sending power then you need to check to make sure the controller had constant power on the black wire and that the red wire gets hot when you press your brake pedal. Obviously if either of those wires aren't working properly the wiring will need to be replaced but if they are working correctly then it sounds like you got a bad brake controller and it needs to be replaced (which is very uncommon for this controller).

If the problem is on your trailer then inspect the wiring from your trailer brakes up to the 7-Way on your trailer looking for and fixing any wiring that is damaged or bent. You can use 10 Gauge Wire # 10-1-1 and Butt Connectors # DW05745-5 to replace any parts that need it.

Let me know if you are still having issues and I can help you troubleshoot further.

expert reply by: Jon G