GM Service Manual Online
For 1990-2009 cars only

Diagnostic Category

Diagnostic Information

DEFINITION: This table consists of eight 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.

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 Incorrect Line Pressure .
    â€¢ Refer to Automatic Transmission Fluid Leaks .
    â€¢ Refer to Fluid Leak Diagnosis .

Noise and Vibration Diagnosis

This category contains the following topics:

    â€¢ Noise - drive gear, final drive, whine, growl, hum, rattle, buzz, popping
    â€¢ Torque converter diagnosis
    â€¢ Noise and vibration analysis
    â€¢ Refer to Popping Noise .
    â€¢ Refer to Buzz Noise or High Frequency Rattle Sound .
    â€¢ Refer to Final Drive Noise or Hum Noise .
    â€¢ Refer to Noise in First, Second, Third, or Fourth .
    â€¢ Refer to Noise in Random Ranges .
    â€¢ Refer to Abnormal Noise in Park or Neutral Range .
    â€¢ Refer to Torque Converter Diagnosis .
    â€¢ Refer to Noise and Vibration Analysis .

Range Performance Diagnosis

This category contains the following topics:

    â€¢ No Park
    â€¢ No Reverse or slips
    â€¢ No Drive or slips
    â€¢ No engine braking
    â€¢ Range selector displays incorrect range
    â€¢ Refer to No Park Range .
    â€¢ Refer to Slips in Reverse or No Reverse .
    â€¢ Refer to Slips in Drive or No Drive .
    â€¢ Refer to Locked Up in Drive/Reverse .
    â€¢ Refer to Range Selector Displays Incorrect Range .

Shift Quality (Feel) Diagnosis

This category contains the following topics:

    â€¢ Harsh shifts
    â€¢ Soft shifts
    â€¢ Harsh engagement, garage shifts
    â€¢ Delayed engagement, garage shifts
    â€¢ Refer to Harsh or Soft 1-2 Shift Feel .
    â€¢ Refer to Harsh or Soft 2-3/3-2 Shift Feel .
    â€¢ Refer to Harsh or Soft 3-4/4-3 Shift Feel .
    â€¢ Refer to Harsh Park to Reverse/Drive Engagement .
    â€¢ Refer to Delayed Park to Reverse/Drive Engagement .

Slipping or Missing Gears

This category contains the following topics:

    â€¢ No upshift
    â€¢ Slipping or missing gears
    â€¢ One forward gear only
    â€¢ Two forward gears only
    â€¢ Non-First gear start
    â€¢ Refer to Slipping or No First Gear .
    â€¢ Refer to Slipping or No Second Gear .
    â€¢ Refer to Slipping or No Third Gear .
    â€¢ Refer to Slipping or No Fourth Gear .
    â€¢ Refer to First Gear Only .
    â€¢ Refer to Second Gear Only .
    â€¢ Refer to Third Gear Only .
    â€¢ Refer to Fourth Gear Only .

Shift Speed Diagnosis

This category contains the following topic:

Incorrect shift points

Refer to High or Low Upshift or Downshift Speed .

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 shudder
    â€¢ Refer to Torque Converter Diagnosis .
    â€¢ Refer to No Torque Converter Clutch Apply .
    â€¢ Refer to Converter Clutch Stuck On in All Gears .

Symptom Can Not Be Duplicated or Symptom Not Found

This category contains the following topics:

    â€¢ Transmission fluid diagnosis
    â€¢ Road testing
    â€¢ Line pressure diagnosis
    â€¢ Refer to Transmission Fluid Check .
    â€¢ Refer to Road Test .
    â€¢ Refer to Line Pressure Check .