GM Service Manual Online
For 1990-2009 cars only

The following table consists of six diagnostic categories that are located in the left-hand column. Using this column, choose the appropriate category based on the operating conditions of the vehicle or transmission. After selecting a category, use the right-hand column to locate the specific symptom diagnostic information.

Diagnostic Category

Diagnostic Information

Important: The Functional Test Procedure should be performed before beginning any diagnosis. If this procedure has not already been performed, refer to Functional Test .

Fluid Diagnosis

This category contains the following topics:

    â€¢ Fluid condition - appearance, contaminants, smell, overheating
    â€¢ Line pressure - high or low
    â€¢ Low lubrication pressure
    â€¢ Fluid leaks

 

    â€¢ Refer to Transmission Fluid Check .
    â€¢ Refer to Transmission Overheats .
    â€¢ Refer to Low Main Line Pressure in All Ranges .
    â€¢ Refer to Low Lubrication Pressure .
    â€¢ Refer to Fluid Leak Diagnosis .
    â€¢ Refer to Fluid Leaks from Transmission Input .
    â€¢ Refer to Fluid Leaks from Transmission Output .
    â€¢ Refer to Contaminated Transmission Fluid .
    â€¢ Refer to Intermittent Buzzing Noise .

Noise and Vibration Diagnosis

This category contains the following topics:

    â€¢ Noise - drive gear, final drive, whine, growl, rattle, buzz, popping
    â€¢ Vibration

 

    â€¢ Refer to Noise and Vibration Analysis .
    â€¢ Refer to Flex Plate/Torque Converter Vibration Test .

Range Performance Diagnosis

This category contains the following topics:

    â€¢ Drives in Neutral
    â€¢ Excessive creep
    â€¢ Will not shift to Forward or Reverse
    â€¢ Will not stay in Forward or Reverse
    â€¢ Will not make a specific shift

 

    â€¢ Refer to Abnormal Activities or Responses .

Shift Quality - Feel Diagnosis

This category contains the following topics:

    â€¢ Erratic shifts
    â€¢ Harsh, soft, delayed or slipping shifts
    â€¢ Harsh, soft, or delayed engagement

 

    â€¢ Refer to Transmission Does Not Shift Properly .
    â€¢ Refer to Excessive Slippage and Clutch Chatter .

Shift Speed Diagnosis

This category contains the following topic:

Inaccurate or inconsistent shift points

 

Refer to Transmission Does Not Shift Properly .

Torque Converter Diagnosis

This category contains the following topics:

    â€¢ Poor performance
    â€¢ Noise during converter operation
    â€¢ TCC shudder
    â€¢ Shudder after TCC apply
    â€¢ Vibration during converter operation

 

    â€¢ Refer to Torque Converter Diagnosis .
    â€¢ Refer to Flex Plate/Torque Converter Vibration Test .