Buick Regal: DTC C1230 or C1231

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 provide an overview of each diagnostic category.

DTC Descriptors

DTC C1230

Left Rear Drive Clutch System Performance

DTC C1231

Right Rear Drive Clutch System Performance

For symptom byte information, refer to Symptom Byte List.

Circuit/System Description

The rear differential clutch control module detects a series of overheat events that have occurred in the left and right rear differential clutch system. No external circuit diagnosis is involved.

Conditions for Running the DTC

• The engine is running.
• The engine speed is above 400 rpm.

Conditions for Setting the DTC

C1230 54

The rear differential clutch control module detects a series of overheat events on the left clutch.

C1231 54

The rear differential clutch control module detects a series of overheat events on the right clutch.

Action Taken When the DTC Sets

• The electronic limited slip control is disabled.
• The AWD SERVICE message is displayed in the driver information center.

Conditions for Clearing the DTC

• The condition for the DTC is no longer present.
• The DTC is not detected in 40 ignition cycles.

Diagnostic Aids

Excessive differentiation (wheel/tire slip) can cause high temperatures in the rear drive axle and DTC C1230 or C1231 may set.

Reference Information

Schematic Reference

Rear Axle Wiring Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEW INDEX

Master Electrical Component List

Description and Operation

Rear Drive Axle 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 DTC C1230 or C1231 is not set.

• If any of the DTCs are set

1. Ignition OFF.
2. Allow 30 min for the clutch to cool completely down.
3. Perform key cycle, ignition OFF then ON.
4. Clear DTC.
5. Verify DTC C1230 or C1231 is not set.
   • If any of the DTCs are set, replace K47 Rear Differential Clutch Control Module.
   • Go to next step: If none of the DTCs are set.
6. All OK.

• Go to next step: If none of the DTCs are set

3. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

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

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