Troubleshooting Trailer Brake Controller
Question:
Question: Hi, i am having trouble with my trailer brakes, i have already replaced the magnets and the drum hubs, and my trailer will only brake with the trailer brake control by hand not when i press my truck brake pedal. There is voltage from the brake pedal ! Thank you
asked by: Peter S
Expert Reply:
Since you have replaced the brake magnets you will need to find out if the issue is on the brake controller, truck, or trailer. To test the brake controller, 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.
If the controller tests fine, 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.
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 as well. 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.
I have also attached some help articles on testing and troubleshooting brake controllers for you to check out which I strongly recommend reading.
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