Code A021 - Left Front Wheel Speed Is Zero: Notes

Wheel sensors produce AC voltage signal as magnetic teeth pass coil. The AC voltage created enables EBCM to determine wheel RPM. EBCM compares individual wheel speed data to detect wheel lock-up.

This test isolates circuit faults causing EBCM to calculate wheel speed to be zero. Code A021 detects open or short to ground and short to voltage. Code is set if EBCM detects 0-MPH speed at left front wheel, while speeds at remaining wheels are greater than 5 MPH and operating correctly.

1. This step determines if Code A032 is present.
2. This step determines if fault is currently present.
3. This step checks for apparent physical damage that may cause code to set.
4. This step determines if sensor internal resistance is correct.
5. This step determines if sensor circuit has continuity.
6. This step determines if sensor circuit is shorted internally.
7. This step checks for open in wheel speed signal high circuit.
8. This step checks for open in wheel speed signal low circuit.
9. This step ensures Code A021 is not caused by poor connections between EBCM and connector.