GM Service Manual Online
For 1990-2009 cars only

Symptom Diagnosis

Diagnostic Category

Diagnostic Information

DEFINITION: This table consists of 9 diagnostic categories that are located in the left 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 column to locate the specific symptom diagnostic information.

Fluid Diagnosis

This category contains the following topics:

    â€¢ Fluid condition: appearance, contaminants, smell, overheating
    â€¢ Line pressure: high or low
    â€¢ Fluid leaks
    â€¢ Refer to Transmission Fluid Check .
    â€¢ Refer to Oil Pressure High or Low .
    â€¢ Refer to Fluid Leak Diagnosis .
    â€¢ Refer to Oil Out the Vent .

Noise and Vibration Diagnosis

This category contains the following topics:

    â€¢ Ratcheting noise
    â€¢ Noise: drive gear, final drive, whine, growl, rattle, buzz, popping
    â€¢ Vibration
    â€¢ Refer to Ratcheting Noise .
    â€¢ Refer to Ticking Noise in Reverse.
    â€¢ Refer to Popping Noise .
    â€¢ Refer to Buzz Noise or High Frequency Rattle Sound .
    â€¢ Refer to Noise in Random Ranges .

Range Performance Diagnosis

This category contains the following topics:

    â€¢ Drives in Neutral
    â€¢ No Park
    â€¢ No Reverse
    â€¢ No Drive
    â€¢ No engine braking
    â€¢ Shift selector indicator does not match transmission gear range
    â€¢ Lack of power or hesitation
    â€¢ Refer to Drives in Neutral .
    â€¢ Refer to No Park .
    â€¢ Refer to No Reverse or Slips in Reverse .
    â€¢ Refer to No Drive in All Ranges .
    â€¢ Refer to No Drive in Drive Range .
    â€¢ Refer to No Overrun Braking - Manual 3-2-1 .
    â€¢ Refer to Range Selector Displays Incorrect Range .
    â€¢ Refer to Lack of Power or Hesitation .

Shift Quality (Feel) Diagnosis

This category contains the following topic:

    â€¢ Harsh, soft or slipping shifts
    â€¢ Harsh, soft or delayed engagement
    â€¢ Shift shudder, flare or tie-up
    â€¢ Refer to Harsh Shifts .
    â€¢ Refer to Slipping or Harsh 1-2 Shift .
    â€¢ Refer to No 3-4 Shift, Slips or Rough 3-4 Shift .
    â€¢ Refer to Harsh Garage Shift .
    â€¢ Refer to Delay in Drive and Reverse .
    â€¢ Refer to 3-2 Flare or Tie-Up .

Shift Pattern

This category contains the following topics:

    â€¢ One forward gear only
    â€¢ Two forward gears only
    â€¢ Gear missing or slipping
    â€¢ No upshift or slipping upshift
    â€¢ No downshifts
    â€¢ Non-First gear start
    â€¢ Refer to First Gear Range Only - No Upshift .
    â€¢ Refer to Third Gear Only .
    â€¢ Refer to Slips in First Gear .
    â€¢ Refer to Slipping or Harsh 1-2 Shift .
    â€¢ Refer to No 3-4 Shift, Slips or Rough 3-4 Shift .
    â€¢ Refer to No Part Throttle or Delayed Downshifts .
    â€¢ Refer to Second Gear Start .

Shift Speed Diagnosis

This category contains the following topic:

Inaccurate or inconsistent shift points

Refer to Inaccurate Shift Points .

Torque Converter Diagnosis

This category contains the following topics:

    â€¢ Torque converter diagnosis
    â€¢ TCC does not apply
    â€¢ TCC does not release
    â€¢ TCC apply/release quality
    â€¢ Refer to Torque Converter Diagnosis .
    â€¢ Refer to No Torque Converter Clutch Apply .
    â€¢ Refer to No Torque Converter Clutch Release .
    â€¢ Refer to Torque Converter Clutch Shudder .

Indicator On or Message Center Displays Message

This category contains the following topics:

Message Center displays "change trans fluid"

Refer to Transmission Component and System Description .

If symptom is not found

    â€¢ Refer to Transmission Fluid Check .
    â€¢ Refer to Road Test .
    â€¢ Refer to Line Pressure Check .