C1234

Circuit Description
As the wheel spins, the wheel speed sensor produces an AC signal. The EBCM uses the frequency of the AC signal to calculate the wheel speed.

Conditions for Running the DTC
The ignition is ON.

Conditions for Setting the DTC
One of the following conditions exists for 0.02 seconds:
^ A short to voltage - the wheel speed sensor signal circuit and wheel speed sensor return circuit voltages are both greater than 4.25 volts.
^ A short to ground - the wheel speed sensor signal circuit and wheel speed sensor return circuit voltages are both less than 0.75 volts.
^ An open - the wheel speed sensor signal circuit voltage is greater than 4.25 volts and wheel speed sensor return circuit voltage is less than 0.75 volts.

Action Taken When the DTC Sets
If equipped, the following actions occur:
^ The EBCM disables the ABS/TCS/VSES for the duration of the ignition cycle.
^ The DRP does not function optimally.
^ The ABS indicator turns ON.
^ The TRACTION CONTROL indicator turns ON.
^ The DIC displays the SERVICE STABILITY SYS message.

Conditions for Clearing the DTC
^ The condition for the DTC is no longer present (the DTC is not current) and you used the scan tool Clear DTC function.
^ The condition for the DTC is no longer present (the DTC is not current) and you used the On-Board Diagnostics Clear DTC function.
^ The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids
If the customer comments that the ABS indicator is ON only during moist environmental conditions (rain, snow, vehicle wash, etc.), inspect the wheel speed sensor wiring for signs of water intrusion. If the DTC is not current, clear all DTCs and simulate the effects of water intrusion by using the following procedure:
1. Spray the suspected area with a 5% saltwater solution. To create a 5% saltwater solution, add 2 teaspoons of salt to 354 ml (12 oz.) of water.
2. Test drive the vehicle over various road surfaces (bumps, turns, etc.) above 40 km/h (25 mph) for at least 30 seconds.
3. If the DTC returns, replace the suspected wheel speed sensor or repair the wheel speed sensor wiring.
4. Rinse the area thoroughly when completed.

Test Description
The number below refers to the step number on the diagnostic table.
2. This step tests for an open in the wheel speed sensor and the wheel speed sensor signal circuits.