Do Electric Trailer Brakes Need to be Changed in Pairs?

Updated 05/24/2018 | Published 05/23/2018

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etrailer Electric Trailer Brakes - 7" - Left/Right Hand Assemblies - 2,000 lbs

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$95.79

Hook Probe Circuit Tester

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Question:

I changed out the left side brake assembly. Prior to reinstalling the drum I hooked up to my truck and try the brakes to see if magnet would energize. It works fine. When I reinstall the drum Im getting message on my truck at the trailer brake is not connected and Brake does not work. If the brake assembly on the other side is bad would it effect the function of the left side brake? I am baffled.

asked by: Ric

Expert Reply:

Electric brakes do not each have to be changed in pairs, so that would not be the cause of the error message. I am not sure what brake controller you have, but there is some troubleshooting you can do.

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 # 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 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