Trailer Brakes Lock Up when Stepping on Brake Pedal on a 1999 Ford F-250

Question

Question:

I have a 1999 Ford F-250 that I bought used, with the Draw Tite actuator already installed. I have owned the truck over 16 years if that gives an indicator of the age of the unit. I towed a cargo trailer this past weekend, and the brakes locked every time I applied my brakes to the point of sliding the tires. I adjusted both switches in every configuration but have the same issue, although there was a little improvement at the least setting. Is it time to replace my unit, and if so, will the plug match up to what I have?

asked by: Lyndell E

0

Expert Reply:

The Draw-Tite Activator brake controllers are time delay controllers meaning that they send back a pre-determined amount of power to the trailer brakes no matter how hard you are braking in your 1999 Ford F-250. If the controller is set to high output then it could lock the brakes even if you only slightly touch the brake pedal. The other adjustment controls how quickly the controller ramps up to the power level it is set at.

If could be that the contacts on the inside are dirty can causing the controller to not work quite right. Moving the various levers numerous times, including the manual override lever, will clean the contacts. If that does not work then something else is going on and there is some testing you can do.

In the truck cab you will need to sever the blue wire several inches from the back of the controller. Then use a circuit tester such as # PTW2993 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 something wrong with the controller and it will need to be replaced.

If it tests fine then reconnect the blue wire. Then move on to the truck side trailer connector. Many times, dirt or corrosion can cause a short in a trailer connector. Make sure the truck and the trailer side connectors are clean and free of corrosion inside and out.

You can test the brake output pin and 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 track down.

If the truck side checks out fine then it could be the wiring to the brake magnets or the magnets themselves. Inspect the power wires to the magnets and look for pinched, frayed, or damaged wires and fix as needed. Make sure the ground wires are attached to clean and corrosion free bare metal surfaces.

You can visually inspect the magnets and if you can see the copper windings coming through the magnets will need to be replaced. To further test the magnets you can follow the help article I have linked. I have also included some help articles on testing and troubleshooting brake controllers for you.

If you determine that a new brake controller is the way to go I recommend the P2 # 90885 because it is easy to set up and use and it is reliable. Also it is a proportional controller so it will apply the trailer brakes as hard as you are braking in the truck. This controller plugs into your truck using harness # 3035-P so if that is the harness you have it will fit this controller as well.