How to Troubleshoot a Trailer Break-away Switch

by Thomas West

Most larger trailers have electric drum brakes that are activated by an electronic brake controller mounted in the tow vehicle. As an added safety feature, you might need to have a break-away switch. The break-away switch is mounted on the front of the trailer tongue and has a thin cable that is connected to the hitch or rear bumper of the tow vehicle. If the trailer comes unattached from the tow vehicle while traveling, the thin cable pulls on the switch and activates the electric trailer brakes, which should stop the trailer immediately and keep it from free-wheeling down the highway. Test your break-away switch before each trip to ensure it works properly.

Hitch the trailer to the tow vehicle as if your were preparing for a trip. Leave the electrical cord from the trailer disconnected from the tow vehicle's receptacle.

Locate the battery compartment near the trailer tongue. Release the retaining strap and remove the cover.

Loosen the battery cable clamps with a wrench. Lift the battery cables straight up from the battery. Use a battery terminal brush to clean the battery terminals and the inside bore of the battery cable ends. Replace the cables and tighten the clamps with a wrench. Skip this step if your battery terminals are clean.

Place a digital voltmeter on the battery terminals to determine the state of the charge of the battery. Charge the battery with a battery charger if the voltage is below 12.5 volts. Replace the battery cover.

Locate the break-away switch on the trailer tongue. Note that the switch is approximately two to three inches long, rectangular and has a thin metal cable protruding from it.

Locate the pin on the switch that the cable is connected to. Pull the switch out to its first notch. Note that it will take about 20 pounds of pull to get the switch out. Listen for a click at the trailer wheels to indicate that the electric trailer brakes have been applied.

Try to drive the tow vehicle forward a short distance to test the trailer brakes. Note that the tow vehicle should not move. Have the trailer brakes adjusted if it does move.

Push the pin back in on the break-away switch. Disconnect the tow vehicle from the trailer.

Items you will need

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