For 1990-2009 cars only
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 C0550 35: ROM Checksum ErrorDTC C0550 39: Internal Comm. Error
Circuit/System Description
The rear differential clutch control module (CCM) detects an internal malfunction.
Conditions for Running the DTC
The ignition switch is in the ON position.
Conditions for Setting the DTC
An internal CCM malfunction exists.
Action Taken When the DTC Sets
One or more of the following actions may occur:
| • | All Wheel Drive Off (AWD Disabled) DIC message. |
| • | Service All Wheel Drive (Service AWD) DIC message. |
Conditions for Clearing the DTC
| • | The condition for the DTC is no longer present. |
| • | The DTC is not detected in 40 consecutive drive cycles. |
Reference Information
Schematic Reference
Connector End View Reference
Transfer Case Control Connector End Views
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
Verify that DTC C0550 is not set.
If the DTC is set, calibrate the CCM. If the DTC resets, replace the CCM.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for CCM replacement, setup, and programming
