When Monitored and Set Condition

1. When Monitored (Supply circuit): Ignition on. The Controller Antilock Brake (CAB) monitors the wheel speed circuit every 7 milliseconds (ms).
2. When Monitored (Signal circuit): Wheel speed comparison is checked at drive off or every 7 milliseconds (ms). Sensor Signal continuity is checked every 7 milliseconds. Wheel speed phase length supervision is checked every 7 milliseconds.
3. Set Condition (Supply circuit): If the CAB detects an open or shorted wheel speed sensor circuit, the Diagnostic Trouble Code (DTC) will set.
4. Set Condition (Signal circuit): If, during an ABS stop, the CAB commands any valve solenoid on for an extended length of time, and does not see a corresponding wheel speed change, the Diagnostic Trouble Code (DTC) is set. The DTC can also set if the Signal is missing or erratic.

POSSIBLE CAUSES
LEFT FRONT WHEEL SPEED SENSOR 12 VOLT SUPPLY CIRCUIT SHORT TO VOLTAGE
LEFT FRONT WHEEL SPEED SENSOR 12 VOLT SUPPLY CIRCUIT SHORT TO GROUND
LEFT FRONT WHEEL SPEED SENSOR 12 VOLT SUPPLY CIRCUIT OPEN
LEFT FRONT WHEEL SPEED SENSOR SIGNAL CIRCUIT SHORT TO GROUND
LEFT FRONT WHEEL SPEED SENSOR SIGNAL CIRCUIT SHORT TO VOLTAGE
LEFT FRONT WHEEL SPEED SENSOR SIGNAL CIRCUIT OPEN
LEFT FRONT WHEEL SPEED SENSOR CIRCUITS SHORT TOGETHER
SENSOR OR TONE WHEEL DAMAGE
WHEEL SPEED SENSOR
CONTROLLER ANTILOCK BRAKE (CAB)

For a complete Antilock Brake System (ABS) Circuit Diagram (Refer to BRAKES/ELECTRICAL - SCHEMATICS AND DIAGRAMS) .