No Power to Trailer Brakes With P2 Brake Controller on 2019 F-150

Question:

I bought a P2 brake controller along with the adapter plug for my 2019 F150. I have trailer lights when hooked to multiple trailers but I have no brakes. The controller always reads that it’s not hooked up to a trailer. Not sure if it’s a fuse issue I check the plug connections. Stumped as to why I would have lights but no brakes. Even when hooked to a trailer and squeezing the brakes manually by hand on the controller still no brakes.

asked by: Scott M

Expert Reply:

Hey Scott,

With no power to the brakes on your F-150 with the P2 Brake Controller # 90885, you will need to find out if the issue is on the brake controller, your truck, or the trailer. To test the brake controller, sever the blue wire a couple inches from the back of your controller. Then use a circuit tester to test the end of the blue wire coming out of the controller. It should only have power when you apply the manual override; if it shows power at idle then there is an issue with the controller and it will need to be replaced.

If the controller tests fine (which I think it likely will since it's newer), reconnect the blue wire and move on to the truck side trailer connector. Often, corrosion or dirt may be the cause of a short in a trailer connector. Check the plug to see if there is any type of corrosion built up that may be hampering its functionality; if so you can replace it with # HM40975.

You will also want to test the brake output pin on the 7-way socket; it should only show power with the manual override. If it shows power any other time then there is a short somewhere between the connector and the brake controller you will need to find.

If the truck side checks out then it could be the wiring to the brake magnets or possibly the magnets themselves. Inspect the power wires to the magnets and look for wires that may be pinched or otherwise damaged and fix as necessary. You'll also need to make sure the ground wires are attached to bare metal surfaces and free of any paint, dirt or corrosion.

You'll want to visually inspect the magnets; if you can see the copper windings coming through the magnets will need to be replaced. I have also attached some help articles on testing and troubleshooting brake controllers for you to check out which I recommend reading.