For 1990-2009 cars

### 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 C0561 71: System Disabled Information Stored invalid serial data received

### Circuit/System Description

The Rear Differential Clutch Control module (RDCCM) receives messages from other modules over GMLAN which are needed to perform all wheel drive functions

### Conditions for Running the DTC

• | The ignition switch is in the ON position.

• | Ignition voltage is greater than 9 volts.

### Conditions for Setting the DTC

The RDCCM receives an invalid message from PCM, EBCM, modules over GMLAN which causes the RDCCM to deactivate.

### Action Taken When the DTC Sets

One or more of the following actions may occur:

• | All Wheel Drive Off (AWD Disabled).

• | Service All Wheel Drive (Service AWD).

### Conditions for Clearing the DTC

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

• | The DTC is not detected in 40 consecutive drive cycles.

### Diagnostic Aids

DTC C0561 is an indicator that the RDCCM receives an invalid message from the ECM, or EBCM , and does not necessarily indicate a fault is present with the RDCCM. This DTC should not be used as a fault indicator, but rather as a symptom to assist in the diagnosis of these other systems.

### Reference Information

#### Schematic Reference

All-Wheel Drive Schematics

#### Connector End View Reference

Transfer Case Control Connector End Views

#### Description and Operation

All-Wheel Drive Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Scan Tool Data List for Scan Tool Information

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for RDCCM replacement, setup, and programming