DTC 21 - Left Front Wheel Speed=0: Notes

As a toothed ring passes the wheel speed sensor, changes in electromagnetic field cause sensor to produce an AC voltage signal. Frequency of signal is proportional to wheel speed. Magnitude of signal is directly related to wheel speed and the proximity of the wheel speed sensor to the toothed ring. This distance is also referred to as "air gap" DTC can be set when vehicle is not in an ABS stop. If the sensors speed is zero for 1.6 seconds and the other 2 wheel speeds are greater than 5 MPH, a malfunction exists.

1. Identifies a wheel speed sensor or sensor circuit that is visibly damaged.
2. Checks wheel speed sensor for proper resistance.
3. Ensures wheel speed sensor and sensor ring generate the proper voltage.
4. Ensures wheel speed sensor circuit is not shorted together. Tester J 39200 is a DVOM with a 10-megohm input impedance.
5. Ensures malfunction was not set due to a poor connection.