Over 8600 GVW or Rear Drum Brakes

DTC C0241-C0254 (Over 8600 GVW or Rear Drum Brakes)

Circuit Description
As the front wheels spin, each Wheel Speed Sensor (WSS) produces an AC signal. The Electronic Brake Control Module (EBCM) uses the frequency of the AC signals to calculate each wheel speed. The Powertrain Control Module (PCM) converts the signal from the Vehicle Speed Sensor (VSS) to a 128k pulses/mile signal. The EBCM uses the vehicle speed signal from the PCM to calculate the rear wheel speed.

DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0245 Wheel Speed Sensor Frequency Error

Conditions for Running the DTC
^ The ignition is ON.
^ The vehicle speed is greater than 8 km/h (4 mph).
^ No brake application or deceleration is detected.
^ No wheel slip is detected.
^ No turning maneuvers are detected.

Conditions for Setting the DTC
^ At least one WSS signal is 15 percent less than or greater than other WSS signals.
^ All of the Conditions for Running and Setting the DTC are present for a cumulative time of 3 minutes during a single ignition cycle.

Action Taken When the DTC Sets
^ The EBCM disables the ABS and Dynamic Rear Proportion (DRP).
^ The ABS indicator turns ON.
^ The brake warning 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 this DTC 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 WSS or VSS 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.