DTC 25 Left Front Wheel Speed Sensor Circuit Fault: Notes

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

EBCM uses wheel speed sensor signal to calculate vehicle reference speeds and individual speed, acceleration and slip values for each wheel. These values are used to determine when anti-lock control is needed.

EBCM performs 2 basic types of checks on wheel speed sensors: sensor continuity and sensor output.

25 will set if short to battery voltage or ground exists in circuit No. 830 or 873. Faulty wheel speed sensor will also set 25. Testing occurs when vehicle is moving. Fault will not set with ignition on and vehicle at rest.

NOTE: To prevent electro-magnetic interference, wheel speed sensor wires are twisted together 9 times per foot of wire. If repairs are necessary, ensure wires are properly twisted, routed and secured.

NOTE: Test numbers refer to numbers on diagnostic chart.

Checks for short to battery voltage in either wheel sensor circuit wires.
Checks for short between wheel speed sensor circuit wires.
Checks for short to ground in wheel speed sensor circuit wires.
Checks if resets during road test.
Checks wiring and connectors for intermittents.
Replace wheel bearing/speed sensor assembly. If resets, EBCM is concluding fault is present when no fault is present.
Ensures is not due to electro-magnetic interference.