How to Troubleshoot Locked Up Tractor Trailer Brakes

Take your vehicle to a mechanic immediately if troubleshooting fails.

Tractor trailers, like any vehicle, sometimes suffer from mechanical problems, such as locking brakes. These brakes must be fixed before using the vehicle because improperly functioning brakes can lead to devastating accidents. If these simple steps do not help eliminate the problem of locked up brakes, take your vehicle to a mechanic. Drive only on your private property while troubleshooting. If troubleshooting fails, tow your tractor trailer to a mechanic.

Things You'll Need

• Wrench

Instructions

1. Pull the parking brake. Turn the trailer on and press the brake pedal with your foot. Press and release the pedal several times. This may unlock brakes.

2. Disconnect the parking brake and drive around a nearby parking lot, attempting to brake. It the tractor still will not brake, pull the parking brake and turn off the trailer.

3. Step off the tractor and look under the its real axle. Adjust the distance between the jam but and the operating arm. Measure the distance with a tape measure and adjust it with a wrench. The jam nut should be 1.5 inches from the operating arm. Remeasure the distance after adjusting to ensure that it is 1.5 inches.

4. Turn the tractor on and press the brake. It should no longer lock up.

Tips & Warnings

• Tow your tractor to a parking lot if there is not one nearby.

References

• Ron's Pit Stop: Troubleshooting the Brake System
• Meritor Wabco: Tractor Troubleshooting Guide
• Dummies: How to Troubleshot Brakes