GM Service Manual Online
For 1990-2009 cars only

Review the system and operation in order to familiarize yourself with the system functions. Refer to Locking Differential Description and Operation .

Visual/Physical Inspection

    • Inspect the system for the following:
       - Loose or missing fasteners
       - Obvious damage or conditions which may cause the symptom.
    • Check the system for proper operation. Refer to Locking Differential Diagnosis .

Symptom List

Refer to a system diagnostic procedure from the following list in order to diagnose the symptom:

    •  Electronic Rear Differential Lock Will Not Engage
    •  Electronic Rear Differential Lock Will Not Disengage