Service Information

Volt

DTC C0245, C122E

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC C0245 00: Wheel Speed Sensor Frequency Error

DTC C122E: Tyre Size Mismatch

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

Conditions for Running the DTC

•	Vehicle On or Vehicle in Service Mode.

•	Ignition voltage is greater than 10 V.

•	Vehicle must be moving at a speed less than 14.5 km/h (9 mph).

•	No wheel speed sensor faults are set.

•	Brake is not applied.

•	Vehicle is not cornering.

•	No wheel spinning is detected.

Conditions for Setting the DTC

•	Missing tooth or teeth on the wheel speed sensor tone ring.

•	The wheel speed differences between one wheel and the others is greater than 25 percent.

Action Taken When the DTC Sets

•	The ABS indicator turns ON.

•	The red brake indicator turns ON.

•	The traction control/stability control indicator turns ON.

•	The Service Brake Assist and Service StabiliTrak messages are displayed on the driver information centre.

•	The electronic brake control module disables the antilock brake system, the dynamic rear proportioning, the traction control system and the electronic stability program for the duration of the drive cycle.

Conditions for Clearing the DTC

•	The condition for setting the DTC is no longer present.

•	The history DTC will clear after 40 consecutive fault-free drive cycles have occurred.

Diagnostic Aids

•	A faulty wheel speed sensor will not set this DTC.

•	A vehicle using a space saver spare will not set this DTC.

Reference Information

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Verify that all tyres have the proper air pressure.

⇒	*If not the proper air pressure*

Adjust the air pressure in all tyres to the stated cold air pressure as identified on the tyre placard or specification.

⇓	*If the proper air pressure*

Verify that all tyres are of uniform size and matching brand.

⇒	*If not of uniform size or matching brand*

2.1.	Replace the mis-sized or non-matching brand tyre.

2.2.	Vehicle in Service Mode.

2.3.	Verify the DTC does not set while operating the vehicle under the Conditions for Running the DTC.

⇒	If the DTC is set, replace the K17 electronic brake control module.

⇓	If the DTC does not set

2.4.

All OK.

⇓	*If all tyres are of uniform size or matching brand*

All OK.