P3 Trailer Brake Controller Will Not Lock Up Trailer Brakes

Updated 04/14/2014 | Published 04/12/2014

Question:

Hi guys Just got my P3 brake controller and installed, very nice unit. I was planning to do the adjustment for my trailer according to the book but are some differences ....the book says that after installation with the engine running adjust the power till I see 6.0 ...- no such-thing as 6.0 when I try to adjust the power will show 14.00 Volt maximum power and nothing else .... When I am driving with the trailer and use the manual override to see if the brake will lock the wheels will not lock them ....? why? On the trailer the brakes are adjusted as necessary mechanically so I can hear a little noise as the pad touching the drum a little. I measured with a multi-meter the volts at the connector when the manual override is used and I have 15Volts which is good. I can not make the p3 to lock the trailer wheels. How do I know if the controller is adjusted properly? I have a 6x10 cargo trailer transformed to a hunting trailer and the weight is aprox.900KG

asked by: Attila K

Expert Reply:

The voltage display that you are seeing could actually be the voltage into the controller. It is reading the voltage from the battery and when a vehicle is running you do typically see around 14 volts.

Unplug the controller for about 15 minutes and then plug it back in. Then start from scratch as far as the initial set up goes. Make sure that boost is not on prior to setting the power level.

On the set up screen you will select brake type, then electric brakes, and then confirm. Make sure the boost level is off (there should be no B1, B2, or B3 displayed). Then you will follow the set up instructions.

Plug in trailer, start the vehicle, adjust power to read 6.0. Then you will do the load speed test and eventually get the brakes to a point just under lock up.

If you are measuring 15 volts at the trailer connector that is actually excessive. It should be around 12 volts with the controller set to the maximum. It suspect a short. A short can occur from a dirty or corroded trailer connector. Make sure the vehicle and trailer side connectors are clean and free of corrosion inside and out.

On the trailer side make sure that the brake magnet power wires are not pinched or frayed and that the magnet ground wires are attached to a clean and corrosion free bare metal surface near the magnets. Visually inspect the magnets and if you can see the copper windings coming through then the magnets will need to be replaced to further test the magnets and brake controller you can follow the help articles I have linked for you.

expert reply by: Michael H