21, 25, or 35, Sensor Open

NAME OF CODE:
21 Right Front Sensor Open
25 Left Front Sensor Open
35 Rear Sensor Open


SET CONDITION:
1. There is no output signal from any sensor for an initial 1.0 second period.
2. There is continuously excessive sensor resistance for a subsequent 1.0 second period.

THEORY OF OPERATION:
The CAB continuously monitors the wheel speed sensor circuits. The CAB sends a small signal (trigger) pulse through the sensor circuits. If the CAB does not receive the proper signal back, a Sensor Open code is set.

POSSIBLE CAUSES:
- Open circuit in sensor or sensor wiring (including connectors)
- Wheel speed sensor (+) circuit shorted to battery voltage
- CAB's internal wheel speed sensor IC shorted

NOTE: Front wheel speed sensors have a resistance of 1000 to 2500 ohms.