C122E

DTC C0245, C122E

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 Instructionsprovides an overview of each diagnostic category.

DTC Descriptors
DTC C0245 00
- Wheel Speed Sensor Frequency Error

DTC C122E
- Tire Size Mismatch

Circuit/System Description

The wheel speeds are detected by active wheel speed sensors. Each wheel speed sensor receives ignition 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

* Ignition ON.
* Ignition voltage is greater than 10 volts.
* 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

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

Action Taken When the DTC Sets

* The EBCM disables the antilock brake system (ABS), traction control and the vehicle stability enhancement system (VSES) for the duration of the ignition cycle.
* A driver information center message and/or a warning indicator may be displayed.

Conditions for Clearing the DTC

* The condition for setting the DTC is no longer present.
* The EBCM clears the history DTC when a current DTC is not detected in 40 consecutive drive cycles.

Diagnostic Aids

* Faulty wheel speed sensor will not set this DTC.
* A vehicle using a space saver spare will not set this code.

Reference Information
Schematic Reference

Antilock Brake System Schematics [1][2]Antilock Brakes / Traction Control Systems
Connector End View Reference

Component Connector End Views Hybrid/EV Battery Pack X1 A4
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 Control Module Referencesfor scan tool information

Circuit/System Verification

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

• If not all the same air pressure, adjust all the tires to the stated cold air pressure as identified on the tire placard or specification.

2. Confirm that all tires are of the proper size and that all are matching brands.

• If a mis-sized or non-matching brand tire is present, inform the customer that in order for the vehicle stability enhanced system to function normally, tires need to be a uniform size and rolling diameter.