Buick Regal: DTC C0242

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 Descriptor

DTC C0242

Powertrain Control Module Indicated Traction Control

For symptom byte information refer to Symptom Byte List.

Circuit/System Description

The electronic brake control module and the engine control module simultaneously control the traction control. The electronic brake control module sends a serial data message to the engine control module requesting torque reduction. When certain engine control module DTCs are set, the engine control module will not be able to perform the torque reduction for traction control. A serial data message is sent to the electronic brake control module indicating that traction control is not allowed.

Conditions for Running the DTC

Engine running

Conditions for Setting the DTC

The engine control module detects a fault that prevents it from performing a traction control function and sends a serial data message to the electronic brake control module indicating that torque reduction is not allowed.

Action Taken When the DTC Sets

The electronic brake control module sends a serial data message to illuminate the appropriate warning/indicator message.

Conditions for Clearing the DTC

• The condition for the DTC is no longer present.
• The electronic brake control module clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids

• Inspect for proper transmission operation.
• Inspect the exhaust system for a possible restriction.
• Inspect for lack of engine power, hesitation, stumble or rough idle.
• Some intermittent communication concerns may be caused by fretting corrosion on the serial data circuit terminals. Inspect all connectors at the control module that set the communication DTC, the control module that the communication DTC was set against, and any inline harness connectors between the two control modules. Do not replace a control module based only on fretting corrosion.

Reference Information

Schematic Reference

Antilock Brake System Wiring Schematics

Connector End View Reference

Component Connector End View Index

Description and Operation

ABS Description and Operation

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

1. Ignition ON.

2. Verify that no other DTCs are set except for C0242.

• If any other DTCs are set

Refer to the Diagnostic Trouble Code (DTC) List - Vehicle.

• Go to next step: If no other DTCs are set

3. Replace the K20 Engine Control Module.

4. Verify that DTC C0242 does not set while operating the vehicle within the Conditions for Running the DTC.

• If DTC sets

Replace the K17 Electronic Brake Control Module.

• Go to next step: If DTC does not set

5. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for electronic brake control module or engine control module replacement, programming and setup.

DTC C0245

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 Descriptor

DTC C0245

Wheel Speed Sensor Frequency

For symptom byte information refer to Symptom Byte List.

Diagnostic Fault Information

Circuit/System Description

Each wheel speed sensor receives ignition voltage through the signal high circuit from the electronic brake control module. Wheel speeds are detected by active wheel speed sensors and encoder rings. The magnetic encoder rings consists of multiple north and south pole pairs surrounding the outer circumference. When the encoder ring rotates and passes by the wheel speed sensor; it generates a sign wave in the wheel speed sensor. The sensor converts the signal to a digital square wave; the square wave values switch between 7mA (Low) and 14mA (High) DC current. As the wheel spins, the module 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 between 20 km/h (13 MPH) and 50 km/h (31 MPH).
• While driving a curve with a yaw-rate of 3º per second for greater than 9 s.

Conditions for Setting the DTC

• A short to voltage on any one of the wheel speed sensor ignition circuits.
• A electrical magnetic interference with the wheel speed sensor harness.
• Difference between the fastest and slowest wheel speed is greater than 6 km/h (4 MPH).
• If two or more wheel speed sensor faults are detected without the ABS warning lamp being turned ON.
• The electronic brake control module cannot determine a specific wheel speed sensor signal because of electrical interference.

Action Taken When the DTC Sets

• The ABS indicator turns ON.
• The traction control Off indicator turns ON.
• The stability control Off indicator turns ON.
• The traction/stability control indicator turns ON.
• The driver information center displays the Service StabiliTrak message.
• The electronic brake control module disables the ABS, the traction control, and the stability control for the duration of the ignition cycle.

Conditions for Clearing the DTC

• When the condition for setting the DTC is no longer present.
• The history DTC will clear after 40 consecutive fault-free ignition cycles have occurred.

Diagnostic Aids

• Do not use a magnet to clean the encoder ring.
• Check for electrical magnetic interference with the wheel speed sensor harness.
• If two 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.

Reference Information

Schematic Reference

Antilock Brake System Wiring Schematics

Connector End View Reference

Component Connector End View Index

Description and Operation

ABS Description and Operation

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

1. Verify that all tires have the proper air pressure.

• If not the proper air pressure

Adjust all tire air pressures to the stated cold air pressure as identified on the tire placard or specification.

• Go to next step: If the proper air pressure

2. Verify that all tires are of uniform size and matching brand.

• If not of uniform size or matching brand

1. Replace the mis-sized or non-matching brand tire.
2. Ignition ON.
3. Verify the DTC does not set while operating the vehicle within the Conditions for Running the DTC.
   • If the DTC set, replace the K17 Electronic Brake Control Module.
   • Go to next step: If the DTC does not set
4. All OK.

• Go to next step: If all tires are of uniform size and matching brand

3. Refer to Circuit/System Testing.

Circuit/System Testing

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the K17 Electronic Brake Control Module, ignition ON.

2. Test for less than 1 V between the K17 Electronic Brake Control Module harness connector terminals listed below and ground:

• B5LF Left Front Wheel Speed Sensor - terminal 7
• B5RF Right Front Wheel Speed Sensor - terminal 26
• B5LR Left Rear Wheel Speed Sensor - terminal 23
• B5RR Right Rear Wheel Speed Sensor - terminal 37
• If 1 V or greater

Repair the short to voltage on the circuit.

• Go to next step: If less than 1 V

3. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for Electronic Brake Control Module replacement, programming and setup

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