C0238

DTC C0238 or C038





Circuit Description
As the front wheels spin, the wheel speed sensors produce an AC signal. The EBCM uses the frequency of the AC signal to calculate the wheel speed. The PCM or vehicle speed sensor buffer (diesel) converts the data from the vehicle speed sensor to a 128k pulses/mile signal. The EBCM uses the vehicle speed signal from the PCM or VSSB in order to calculate the rear wheel speed.

Conditions for Running the DTC
The ignition is ON and the vehicle speed is between 24 km/h (15 mph) and 80 km/h (50 mph).

Conditions for Setting the DTC
The EBCM detects that one wheel speed input is 10 percent greater than or 10 percent less than the other wheel speed inputs within 3.2 km (2 miles) of driving.

Action Taken When the DTC Sets
^ The EBCM disables the ABS.
^ The ABS indicator turns ON.

Conditions for Clearing the DTC
The conditions for setting the DTC are no longer present and you use the scan tool Clear DTCs function.

Diagnostic Aids
Installing one tire of significantly different size on the vehicle causes DTC C0238 to set. Operating the vehicle with a tire that has very low air pressure may also set this DTC. Inspect the vehicle for an incorrect or damaged wheel speed sensor or vehicle speed sensor if the tires and the EBCM and PCM calibrations are OK.

Test Description
The number below refers to the step number on the diagnostic table.
4. If the front tires are not the same size as the rear tires, the EBCM calibration must match the FRONT tire size and the PCM calibration must match the REAR tire size. The VSSB must be replaced when the axle ratio or the rear tire size is changed significantly (diesel).