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Troubleshooting Brake Controller Not Working


I have a brake force controller, it applies a little brake when you apply the brakes with the pedal but manually it works fine. The screen doesnt light up until you push the override. There is very little voltage coming from the brake switch, to the controller as you push the pedal down. Is my brake switch bad or the controller?


Expert Reply:

We do not carry this particular brake controller but there are a number of troubleshooting steps you can go through to find out what the problem is, which may not be the brake switch or the controller at all.

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 a circuit tester such as # 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 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 you can follow the help article I have linked. I have also attached some help articles on testing and troubleshooting brake controllers for you to check out.

expert reply by:
Kyle S

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