How to Test Electric Trailer Brakes

by Dwight Chestnut
itstillruns article image
Jupiterimages/ Images

The heart of a trailer's electrical brake system is the controller, which feeds current into the system and through the electromagnets in the brakes. Once energized, these magnets attach to the brake drum's rotating surfaces and actuating levers to control braking. For this reason, testing electric trailer brakes involves testing and evaluating current flow between the controller and the magnets as well as testing the viability of the controller and magnets.

Step 1

Raise your trailer using a jack and position a jack stand under the frame for support and stability. Refer to your trailer’s documentation for specific recommendations from the manufacturer on lifting and supporting the trailer so you can safely access the brakes.

Step 2

Check the controller current output. Locate the brake controller and disconnect the blue wire from the unit. Connect the ammeter in series with the line where you just removed the blue wire to measure the current flow. Compare the amperage reading to the controller specifications to determine if the controller is producing the required current. If not, refer to the product documentation for instructions on how to troubleshoot the controller.

Step 3

Check the connector if the amperage is not satisfactory after troubleshooting the controller. Remove the connector and check the pins for corrosion, loose connections and general wear. Reinstall the connector and repeat the controller test in Step 2. If the connector is working properly, go on to the next step.

Step 4

Disconnect one of the magnet lead wires and connect an ammeter between the wires. Measure and document the current level. Compare this amperage value to your specifications to determine if the magnets are receiving and processing the required current from the controller based on the size of your brakes. If not, refer to your brake and magnet specifications to learn how to troubleshoot these components for your make and model.

Step 5

Check the wear and tear on magnets as a preventative measure. Use a straightedge tool to check and inspect each magnet by laying the straightedge flat against the surface of the magnet. Abnormal wear will be indicated if the magnet surface deviates from the straightedge at any point. Replace the magnet if abnormal wear is evident. Also, check to see if any part of the magnet coil is visible through the material facing of the magnet. If so, replace the brakes on both sides of the axle.

More Articles

article divider