Malfunctioning Trailer Brakes on a Car Hauler Trailer

Expert Reply:

When dealing with any electrical component problem, I always suggest starting at one end at working your way to the other, step by step. Start at the brakes and check the magnets. They will wear over time and the more they wear, the less they can grab the hub. I will include a link to a video on replacing trailer brake magnets that tells you some of the signs of bad magnets and where to look for them. Also, with the hub off, engage the brake controller and test to see if the magnet charges up by letting it grab a screwdriver or wrench. If the magnets look fine, but do not get a charge, I would check the wiring starting at the magnets and work all the way up to the brake controller.

Check the two wires coming off the magnet. One lead should be connected to a wire that ultimately leads to the brake controller, the other is a ground wire. The closer that ground wire attaches to the magnet or brake assembly, the better. If the magnet leads look good and have solid connections, follow the brake wire all the way up to the 5/6/7 Way connector. Check for worn shielding. If the wire conductor makes contact with the frame it could pull current out of the wire and reduce the signal sent to the magnets. If the wiring from the magnets to the connector is fine, you can move on to wiring on the vehicle side between the brake controller and the connector again checking for loose connections, frayed wires or abrasion on the coating.

If all the wiring and connections look good all the way up to the brake controller, the problem may be the brake controller. Using a circuit tester, make sure the brake controller sends power on the trailer brake wire when you engage it via foot brake or manual brake controller switch. As always check any fuses or breakers on any of the related circuits.

Check the brake controller settings. Make sure nothing got accidentally adjusted.

expert reply by: Patrick B