Tekonsha Primus IQ Not Working with Brake Pedal Pressed on 2011 Ford F-250

Published 10/15/2015

Question:

My truck, 01 F250, had this Primus IQ controller install when I purchased it. It worked great until recently. Now, no matter where I set the gain/boost, it will only apply a small amount of current to the brakes automatically regardless of speed. However with the manual override it will apply as much as I could ask for. It leads me to believe something with the controller could be malfunctioning as my wiring is still delivering the needed current with the manual slide. Is there anything I should check before purchasing a new controller? It should also probably be noted that it has the same symptoms with all my trailers so the problem, Im sure, is at the least somewhere in the truck weather it be controller or somehow wiring. Thanks in advance for any input!

asked by: Michael C

Expert Reply:

On your Primus brake controller and 2001 Ford F-250 make sure that the red wire connection is good. The brake controller should be plugged in using harness # 3035-P. Inspect the pins where it plugs into the truck to make sure everything is in good working order.

If the controller was ever accidently bumped it could have been knocked out of its proper operating orientation. The controller should not be tilted or turned to the side and it needs to be either perfectly level or can tilt as far as 70 degrees. If it is outside of those parameters it can cause this exact problem.

If it continues to behave this way, and since it works with the manual override and all trailers behave the same way, it is likely a problem inside the controller and it will need to be replaced. I recommend the P2 # 90885 because it is easy to set up and use and is reliable. It also uses the same wiring harness as the Primus.

expert reply by: Michael H