GM Service Manual Online
For 1990-2009 cars only

The following table consists of seven 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.

The tables that follow provide more specific information relating to each of the symptoms listed.

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

Diagnostic Category

Diagnostic Information

Fluid Diagnosis

This category contains the following topics:

    • Fluid condition (appearance, contaminants, smell, overheating)
    • Line pressure (high or low)
    • Fluid leaks
    • Refer to Transmission Fluid Check.
    • Refer to Oil Pressure High or Low.
    • Refer to Fluid Leak Diagnosis.
    • Refer to Oil Out the Vent.
    • Refer to Front Oil Leak Diagnosis.

Noise and Vibration Diagnosis

    • Ratcheting noise
    • Noise (drive gear, final drive, whine, growl, rattle, buzz, popping)
    • Vibration
    • Refer to Ratcheting Noise.

Range Performance Diagnosis

This category contains the following topics:

    • Drives in Neutral
    • No Park
    • No Reverse
    • No Drive
    • No engine braking
    • Refer to Drives in Neutral.
    • Refer to No Park.
    • Refer to No Reverse or Slips in Reverse.
    • Refer to No Drive in All Ranges.
    • Refer to No Drive in Drive Range.
    • Refer to No Overrun Braking - Manual 3-2-1.

Shift Quality (Feel) Diagnosis

This category contains the following topics:

    • Harsh, soft or slipping shifts
    • Harsh, soft or delayed engagement
    • Shift shudder, flare or tie-up
    • Refer to Harsh Shifts.
    • Refer to Slipping or Harsh 1-2 Shift.
    • Refer to Harsh Garage Shift.
    • Refer to Delay in Drive and Reverse.
    • Refer to 3-2 Flare or Tie-Up.

Shift Pattern

This category contains the following topics:

    • One forward gear only
    • Two forward gears only gear missing or slipping
    • No upshift or slipping upshift
    • No downshifts
    • No first gear start
    • Refer to First Gear Only.
    • Refer to Third Gear Only.
    • Refer to Slips in First Gear.
    • Refer to Slipping or Harsh 1-2 Shift.
    • Refer to Second Gear Start.

Shift Speed Diagnosis

This category contains the following topic:

Inaccurate or inconsistent shift points

Refer to Inaccurate Shift Points.