Trailer Brakes Disengage After Prodigy P2 Brake Controller is Activated

Published 10/23/2014

Products Featured in This Question

Tekonsha Prodigy P2 Trailer Brake Controller - 1 to 4 Axles - Proportional

(2763)

$159.00

LCD Digital Circuit Tester

(26)

$26.67

Question:

I have a Toyota Landcruiser Series 2 with a Prodigy P2 Electronic Brake Controller towing a dual wheel Caravan. I have had new brake linings and the Magnets checked on each wheel. For some reason when the brakes are applied even with the gain to max 13 the brakes keep disengaging as though the ABS system on the vehicle takes control . The brakes just will not hold on long enough to do any braking. Just wondering if unit could be faulty or unit is wired incorrectly to vehicle although done by Auto Electrician.

asked by: Kevin R

Expert Reply:

When your Prodigy P2 Brake Controller # 90885 is properly installed it will only be connected to your vehicle's braking system by one wire, a wire from the brake light switch on the pedal that tells the controller to apply the trailer brakes. The ABS braking system's action remains limited to the vehicle and does not affect the brake switch or your Prodigy controller.

The best way to troubleshoot is to separate the vehicle and trailer and test each individually. This process is easier if you have a circuit tester like # PTW2992. A video on how to use a tester is linked for your reference.

First, test the 7-way on the vehicle. Have a helper press the manual override lever on the P2. This will send maximum power to the controller and you should detect a signal on the pin at the 5-o-clock position on the 7-way. Please refer to the linked photo. If this signal is present you know the controller is working. If no signal is present at the 7-way you can test the blue output wire on the back of the controller in the same way, using the manual override. If a signal is present there then again the controller is working but there is a problem in the wiring between the P2 and the 7-way; if no signal is leaving the P2 then I suggest you have your installer check his installation. The unit itself could also be malfunctioning. Test the red wire going into the P2 while pressing the brake pedal; if you detect a signal going in on the red wire but nothing coming out on the blue wire then the unit is bad.

On the trailer side you can test the brakes by directly applying 12V power to the trailer connector. You can use a spare 12V battery or use the vehicle battery. Connect the negative terminal to the ground (white) wire on your 7-way trailer plug and the positive terminal to the brake (blue) wire. Your brakes should lock up. If they do then the issue is likely in the vehicle wiring or brake controller itself. If they do not then you have a wiring issue within the trailer or the brake assemblies require adjustment.

Two articles linked to your right that will give you additional troubleshooting help.

expert reply by: Adam R