GM Service Manual Online
For 1990-2009 cars only

Symptoms -- Automatic Transmission

Diagnostic Category

Diagnostic Information

The following table consists of nine 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 diagnostics 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 Fluid Pressure High or Low .
    • Refer to Fluid Leak Diagnosis .
    • Refer to Automatic Transmission Overheating .

Noise and Vibration Diagnosis

This category contains the following topics:

    • Ratcheting noise
    • Noise - drive gear, final drive, whine, growl, rattle, buzz, popping
    • Vibration
    • Refer to Noise and Vibration Analysis .
    • Refer to Popping Noise .
    • Refer to Noise in Random Ranges .

Range Performance Diagnosis

This category contains the following topics:

    • Drives in Neutral
    • No Park
    • No Drive
    • Shift selector indicator does not match transmission gear range
    • Refer to No Drive in All Ranges
        .

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
    • No engine braking
    • Refer to Harsh Shifts .
    • Refer to Harsh Shift 4 to 5, or 5 to 4 .
    • Refer to Harsh Shift D to R .
    • Refer to Degraded 1-2 and 2-1 Shifts .
    • Refer to Degraded 2-3 and 3-2 Shifts .
    • Refer to Slips or Shudders in First Gear .
    • Refer to Degraded 4-5 Shift .
    • Refer to No Engine Braking in Second Gear .
    • Refer to No Engine Braking in Third Gear .
    • Refer to No Engine Braking .
    • Refer to No Engine Braking in First Gear .

Shift Pattern

This category contains the following topics:

    • One forward gear only
    • Two forward gears only
    • Third gear only
    • Gear missing or slipping
    • No upshift or slipping
    • No downshifts
    • Non- First gear start
    • Refer to First and Second Gears Only .
    • Refer to First Gear Only .
    • Refer to First, Fourth, and Fifth Gears Only .
    • Refer to Second and Third Gears Only .
    • Refer to Fifth Gear Only .
    • Refer to No Reverse or Slips in Reverse .
    • Refer to Slips while Shifting .
    • Refer to No Second Gear .
    • Refer to No Third Gear .
    • Refer to No First Gear .
    • Refer to No Fifth Gear .
    • Refer to Slips while Shifting .

Shift Speed Diagnosis

This category consists of the following topic:

Inaccurate or inconsistent shift points

Refer to Inaccurate Shift Points .

Torque Converter Diagnosis

This category contains the following topics:

    • Torque converter diagnosis
    • TCC does not apply
    • TCC does not release
    • TCC apply/release quality
    • Refer to Torque Converter Diagnosis .
    • Refer to Harsh Torque Converter Clutch Apply .

Indicator ON or Message Center Displays Message

This category contains the following topics:

    • Change transmission fluid light ON
    • Service transmission light ON
    • Transmission hot idle engine light ON

Refer to Transmission Indicators and Messages .

If Symptom Not Found

Transmission will not upshift or downshift using Driver Shift Control.

    • Refer to Transmission Fluid Check .
    • Refer to Road Test .
    • Refer to Line Pressure Check .
    • Refer to TAP Shift Circuit Performance .