Circuit Description
As the front wheels spin, each wheel speed sensor 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 wheel speed sensor signal is 15 percent less than or greater than, other wheel speed sensor 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/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 wheel speed sensor 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.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics Connector End View Reference: Antilock Brake System Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 | Inspect both of the front tires on the vehicle to ensure that both tires are of equal size. Are both of the front tires of equal size? | Go to Step 3 | Go to Diagnostic Aids |
3 | Inspect both of the rear tires on the vehicle to ensure that both tires are of equal size. Are both of the rear tires of equal size? | Go to Step 4 | Go to Diagnostic Aids |
Verify the electronic brake control module (EBCM) and the powertrain control module (PCM) both have the correct tire size calibration. Use the scan tool in order to view the EBCM tire size calibration or perform the Tire Size Calibration procedure and refer to Diagnostic System Check - Vehicle . Did you find and correct the condition? | Go to Step 5 | Go to Diagnostic Aids | |
5 |
Does the DTC reset? | Go to Step 2 | System OK |
