Unable to Lower Power Level on Tekonsha Primus IQ Brake Controller

Question:

Hello - I am setting up the Primus iq for the first time and I am unable to set the power level. When I roll the dial, it goes from 0.0 to 12 or 14 every time, it does not let me stop in between. What may be causing this? Thanks!

asked by: Brian M

Expert Reply:

It sounds like something is drawing full power on the brake output of your Tekonsha Primus IQ Brake Controller # TK90160. This is most likely the reason why the display is showing 12. According to the User Manual, the power output range is from 0.0 to 13. To determine the cause we'll need to test a few things.

Start by severing the blue wire coming out the back of your Primus IQ, leaving a few inches of wire to reconnect later. Use a circuit tester like # PTW2993 to check for power. The blue wire should only be hot when you activate the manual override. If it shows power when idle then there is something internally wrong with the controller and it will need to be replaced.

If the blue wire tests fine then reconnect it and move on to the truck side trailer connector. It's not uncommon for dirt or corrosion to cause a short in a trailer connector. Make sure the truck and the trailer side connectors are clean and free of corrosion inside and out.

You can also test the brake output pin on your 7-way. It should only show power with the manual override. If it shows power any other time then there is a short somewhere between the connector and the brake controller you will need to track down.

I have linked you to a helpful article and video below.

expert reply by: Carla M