Buick Regal: DTC C0055

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 C0055

Rear Wheel Speed Sensor Circuit

For symptom byte information refer to Symptom Byte List.

Circuit/System Description

The wheel speeds are detected by active wheel speed sensors. Each wheel speed sensor receives a 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. The EBCM sends the wheel speed information as a high speed controller area network (CAN) serial data message.

Conditions for Running the DTC

Ignition ON

Conditions for Setting the DTC

A supervised periodic message that includes the wheel speed serial data has not been received.

Action Taken When the DTC Sets

Specific subsystems will not function or operate in degraded mode.

Conditions for Clearing the DTC

A current DTC clears when the diagnostic runs and passes.

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

Diagnostic Aids

This DTC can be set due to an incorrect part wheel speed sensor installed.

Circuit/System Verification

Ignition ON, observe the scan tool EBCM Wheel Speed Sensor parameters. The reading should be the same speed on all sensors when driving in a straight line at a speed greater than 20 km/h (13 MPH).

1. Drive the vehicle in a straight line at a speed greater than 40 km/h (25 MPH).

2. Verify all scan tool Wheel Speed Sensor parameters are within 1.6 km/h (1 MPH) of each other.

• If any parameter is not within 1.6 km/h (1 MPH) of each other.

Refer to Circuit/System Testing.

• Go to next step: If each parameter is within 1.6 km/h (1 MPH) of each other.

3. All OK.

Circuit/System Testing

1. Ignition ON.

2. Verify that DTC C0035, C0040, C0045, or C0050 is not set in the EBCM.

• If any listed DTC is set

Refer to Diagnostic Trouble Code (DTC) List - Vehicle to diagnose that DTC prior to this diagnostic.

• Go to next step: If any listed DTC is not set

3. Replace the K17 Electronic Brake Control Module.

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

• If the DTC sets

Replace the module that set the DTC.

• Go to next step: If the DTC does not set

5. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References provides information for control module replacement, programming and setup.

DTC C005A

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 C005A

Simultaneous Malfunction of Both Wheel Speed Sensors on One Axle

For symptom byte information refer to Symptom Byte List.

Circuit/System Description

The wheel speeds are detected by active wheel speed sensors and encoder rings. The encoder ring consists of permanent magnets. 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 in Service Mode or Vehicle ON
• Ignition voltage is greater than 10 V.
• Two wheel speeds are greater than 5 km/h (3 MPH).

Conditions for Setting the DTC

Simultaneous dropout of both wheel speed sensors on the same axle.

Actions 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 center.
• 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.

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 DTC C005A is not set.

• If the DTC is set

Refer to DTC C0035-C0051 (RPO J69) or DTC C0035-C0051 (RPO J71).

• Go to next step: If the DTC is not set

3. All OK.

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