Premature ABS Cycling

NOTE: When working on a vehicle which has a complaint of premature ABS cycling it may be necessary to use a ORB Scan Tool to detect and verify the condition.

There is one complaint called Premature ABS Cycling in which neither the Red Brake Warning Lamp nor the Amber Antilock Lamp were illuminated and no fault codes were stored in the CAB. Symptoms of Premature ABS Cycling, include clicking sounds from the solenoids valves, pump motor running and pulsations in the brake pedal. This condition can occur at any braking rate of the vehicle and on any type of road surface. This creates an additional condition which needs to be correctly assessed when diagnosing problems with the antilock brake system.

The following conditions are common causes that need to be checked when diagnosing a condition of Premature ABS Cycling. Damaged tone wheels, incorrect tone wheels, damage to a wheel speed sensor mounting boss on a steering knuckle, a loose wheel speed sensor mounting bolt, and excessive tone wheel runout. Also, an excessively large tone wheel to wheel speed sensor air gap can lead to the condition of Premature ABS Cycling. Special attention is to be given to these components when diagnosing a vehicle exhibiting the condition of Premature ABS Cycling. After diagnosing the defective component, repair or replace as required.

When the component repair or replacement is completed, test drive the vehicle to verify the condition of Premature ABS Cycling has been corrected.