Troubleshooting a P3 Brake Controller for a SHORT TO BATTERY Warning on a Dodge 3500

Question:

Have a p3 installed in a dodge 3500 that has a red screen reading WARNING SHORT TO BATTERY and that screen stays on all the time even unhooked from trl. We found some corrosion in the Dodge plug harness and reolaced that. That rectified the problem for 10 minutes and then back saying the same. Popped in a new P3 immediately comes up the same . Can you help?

asked by: GORD

Expert Reply:

It sounds like the problem is corrosion or a short somewhere on the vehicle side of your brake controller wiring. The most obvious place is at the 7-way at the back of your vehicle. I would check the front and the back of the connector for corrosion or exposed wires and fix as necessary.

The P3 will show the short to battery message if the brake control unit is getting a back feed of power on the brake wire. You will want to check and make sure the electric brake wire is ran on its own line throughout the tow vehicle, and to ensure that it has not rubbed through and touching any other power source including the 7-way. If you disconnect the blue wire and display reading goes away you will know that the control should be fine and to check out the wiring of the vehicle.

We have heard of instances of this where the control unit will register this code under excessive moisture and snow conditions. Then when the 7-way dries out the code will disappear.

expert reply by: Jameson C