C0245

DTC C0245

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

DTC Descriptor
DTC C0245 00
- Wheel Speed Sensor Frequency Malfunction

Circuit/System Description

The wheel speeds are detected by active wheel speed sensors. Each wheel speed sensor receives 12 V reference voltage from the electronic brake control module (EBCM) and provides an alternating current square wave signal to the EBCM. As the wheel spins, the EBCM uses the frequency of the square wave signal to calculate the wheel speed.

Conditions for Running the DTC

* DTC C0035, C0040, C0045, or C0050 is not present.
* Vehicle speed is greater than 20 km/h (13 MPH).

Conditions for Setting the DTC

* Difference between the fastest and slowest wheel speed is greater than 6 km/h (4 MPH)
* The EBCM can not determine a specific wheel speed sensor fault.

Action Taken When the DTC Sets

* The EBCM disables the ABS, traction control and stability control for the duration of the ignition cycle.
* The ABS indicator turns ON.
* The traction control/stability control-active indicator turns ON.

Conditions for Clearing the DTC

* A current DTC clears when the diagnostic runs and passes.
* The EBCM will turn OFF the indicators and enable the system functions in the next ignition cycle.

Diagnostic Aids

* Do not use a magnet to clean the encoder ring.
* If 2 or more wheel speed sensors are inoperative, diagnose each wheel speed sensor individually.
* 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.
2. Test drive the vehicle over various road surfaces (bumps, turns, etc.), above 40 km/h (25 MPH) for at least 30 s.
3. Rinse the area thoroughly when completed.

Reference Information
Schematic Reference

Antilock Brake System Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

ABS Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing For Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

Ignition ON, observe the scan tool Wheel Speed Sensor parameters while spinning the wheels. The readings should be analog to the wheel speeds.

Circuit/System Testing

1. Inspect for one tire that has improper air pressure or improper size.

• If not all the same pressure, adjust all tire pressures to specification. If not all the same size, replace the incorrect tire.

2. Inspect the wheel speed sensors for contamination, physical damage and correct installation.

• If contamination, physical damage or incorrect installation is diagnosed, repair or replace the B5 wheel speed sensor and verify the DTC does not reset.

3. If the DTC resets, replace the K17 Electronic Brake Control Module (EBCM).

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Front Wheel Speed Sensor Replacement (Front Wheel Speed Sensor Replacement)
* Rear Wheel Speed Sensor Replacement (Rear Wheel Speed Sensor Replacement)
* Control Module References (Programming and Relearning) for EBCM replacement, programming and setup