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Troubleshooting Trailer Brakes Not Working on Ford Truck


I hooked up a trailer brake control to my 05 f150 with the factory tow package and I have everything working but the trailer brakes. I checked the electric brake fuse and is fine.


Helpful Expert Reply:

If your trailer brakes are not working there are a few troubleshooting steps to take. Start by testing the brake controller itself; sever the blue wire a couple inches from the back of your controller. Then use circuit tester # PTW2979 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.

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.

You will also want to test the brake output pin on the 7-way socket with a circuit tester 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. To test the magnets use Multimeter # PT89ZR and follow the help article I have linked to guide you.

I have also attached some help articles on testing and troubleshooting brake controllers for you to check out which I strongly recommend reading.

helpful expert reply by:
Kyle S

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