How Much Voltage Will be on Blue Wire and 7-Way When Testing Primus IQ Brake Controller

Question:

hi my name is Chris and I have a problem with my Tekonsha primus iq 90160 the unit shows all is ok but I have no brakes either trough the manual slide or the foot brake, I have checked the wiring and both the black wire and red wire worked when unplugged from the unit which are correctly wired, I havent cut the blue wire yet so my question is what should the voltage be at the unit when blue wire is cut and what should it be at the back of the vehicle 7 pin plug, yours in anticipation

asked by: Chris V

Helpful Expert Reply:

You should be seeing about 12V both 6" on the blue wire from the Primus IQ # TK90160 and at the 7-Way on your vehicle (with the brake controller set to the highest setting). By testing the blue wire and your 7-Way connector you can determine if new 10 Gauge Wire # 10-1-1 need to be routed or spliced into the wiring on your tow vehicle or your trailer. If you have voltage at the 7-Way on your vehicle then you know the issue is on your trailer whether it is the trailer connector or the wiring from the 7-Way to your brakes.

Either way, once you run the test on the blue wire and 7-Way for your tow vehicle you should know where the problem is isolated to and you can proceed accordingly.

Please note that the Primus IQ is a proportional controller so you will only see voltage when using the manual override since you are sitting still.

expert reply by: Jon G