GM Service Manual Online
For 1990-2009 cars only

Strategy Based Diagnostics

Review the system operations in order to familiarize yourself with the system functions. Refer to Transfer Case Disassembled View , Transfer Case Description and Operation , and Rear Drive Axle Description and Operation . All diagnosis on a vehicle should follow a logical process. Strategy based diagnostics is a uniform approach for repairing all systems. The diagnostic flow may always be used in order to resolve a system condition. The diagnostic flow is the place to start when repairs are necessary. For a detailed explanation, refer to Strategy Based Diagnosis .

Visual/Physical Inspection

    â€¢ Inspect for aftermarket devices, which could affect the operation of the vehicle. Refer to Checking Aftermarket Accessories .
    â€¢ Inspect the easily accessible or visible system components for obvious damage or conditions, which could cause the symptom.
    â€¢ Inspect for the correct lubricant levels and the proper viscosities.
    â€¢ Verify the exact operating conditions under which the concern exists. Note factors such as vehicle speed, road conditions, ambient temperature, and other specifics.
    â€¢ Compare the driving characteristics or sounds, if applicable, to a known good vehicle and ensure you are not trying to correct a normal condition.

Intermittent

Test the vehicle under the same conditions that the customer reported in order to verify the system is operating properly.

Symptom List

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

    â€¢  Diagnostic Starting Point - Transfer Case
    â€¢  Diagnostic Starting Point - Rear Drive Axle
    â€¢  Noisy in Drive
    â€¢  Noisy When Coasting
    â€¢  Intermittent Noise
    â€¢  Constant Noise
    â€¢  Transfer Case Leak Diagnosis

Strategy Based Diagnostics

Review the system operations in order to familiarize yourself with the system functions. Refer to Transfer Case Disassembled View , Transfer Case Description and Operation , and Rear Drive Axle Description and Operation. All diagnosis on a vehicle should follow a logical process. Strategy based diagnostics is a uniform approach for repairing all systems. The diagnostic flow may always be used in order to resolve a system condition. The diagnostic flow is the place to start when repairs are necessary. For a detailed explanation, refer to Strategy Based Diagnosis.

Visual/Physical Inspection

    â€¢ Inspect for aftermarket devices, which could affect the operation of the vehicle. Refer to Checking Aftermarket Accessories.
    â€¢ Inspect the easily accessible or visible system components for obvious damage or conditions, which could cause the symptom.
    â€¢ Inspect for the correct lubricant levels and the proper viscosities.
    â€¢ Verify the exact operating conditions under which the concern exists. Note factors such as vehicle speed, road conditions, ambient temperature, and other specifics.
    â€¢ Compare the driving characteristics or sounds, if applicable, to a known good vehicle and ensure you are not trying to correct a normal condition.

Intermittent

Test the vehicle under the same conditions that the customer reported in order to verify the system is operating properly.

Symptom List

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

    â€¢  Diagnostic Starting Point - Transfer Case
    â€¢  Diagnostic Starting Point - Rear Drive Axle
    â€¢  Noisy in Drive
    â€¢  Noisy When Coasting
    â€¢  Intermittent Noise
    â€¢  Constant Noise
    â€¢  Transfer Case Leak Diagnosis