Code 27 - Left Front Wheel Speed Sensor Continuity: Notes

Toothed wheel generates a voltage pulse as it moves past wheel speed sensor. EBCM uses the frequency of these pulses to determine wheel speed. Amount of voltage generated in each pulse depends on air gap between wheel speed sensor and toothed wheel and on wheel speed.

SERVICE ABS and SERVICE ASR indicators will be on and Code 27 will be set if speed sensor is faulty or if there is a short to voltage or open in circuit No. 830 or circuit No. 873. Code will set with ignition on and vehicle stopped.

1. Checks for correct resistance reading of wheel speed sensor.
2. Checks for short to battery voltage in wheel speed sensor circuit wires.
3. Checks for open in wheel speed sensor circuit wires.
4. Checks for an intermittent fault that is not currently present.
5. Checks if code resets when ignition is turned on. If Code 27 resets, wheel bearing/speed sensor assembly is most likely at fault.
6. Checks if Code 25 sets during road test.
7. Code 25 sets with a problem in speed sensor circuits when vehicle is moving. Code 27 sets when vehicle is stopped. If Code 25 sets at this point, follow diagnostic chart for Code 25.
8. Intermittent may be caused by wheel speed sensor. If Code 27 is reset after sensor replacement, EBCM is detecting a fault in a speed sensor circuit when one does not exist.