GM Service Manual Online
For 1990-2009 cars only

Diagnostic Category

Diagnostic Information

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.

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 Fluid Foaming .
    â€¢ Refer to High or Low Line Pressure .
    â€¢ Refer to Fluid Leak Diagnosis .
    â€¢ Refer to Automatic Transmission Fluid Leaks .

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 Whine Noise Varying with RPM .
    â€¢ Refer to High Pitch Whine Noise .
    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 Random Ranges .
    â€¢ Refer to Noise in First, Second, Third, or Fourth .
    â€¢ Refer to Noise and Vibration Analysis .
    â€¢ Refer to Vibration .

Range Performance Diagnosis

This category contains the following topics:

    â€¢ Drives in Neutral
    â€¢ No Park
    â€¢ No Reverse
    â€¢ No Drive
    â€¢ Loss of power
    â€¢ No engine braking
    â€¢ Shift indicator indicating wrong gear
    â€¢ No gear selection
    â€¢ Refer to Drives in Neutral .
    â€¢ Refer to No Park .
    â€¢ Refer to No Reverse or Slips in Reverse .
    â€¢ Refer to Loss of Drive .
    â€¢ Refer to Loss of Power .
    â€¢ Refer to Engine Stall .
    â€¢ Refer to No Engine Braking; All Manual Ranges .
    â€¢ Refer to No Gear Selection .

Shift Quality - Feel - Diagnosis

This category contains the following topic:

Harsh shifts

Refer to Harsh Shifts .

Shift Pattern

This category contains the following topics:

    â€¢ One forward gear only
    â€¢ Specific forward gears only
    â€¢ Slipping
    â€¢ Refer to Second Gear Only .
    â€¢ Refer to First and Second Gears Only .
    â€¢ Refer to First and Fourth Gears Only .
    â€¢ Refer to Second and Third Gears Only .
    â€¢ Refer to Third and Fourth Gears Only .
    â€¢ Refer to No First Gear, Slips in First Gear .
    â€¢ Refer to No Second Gear, Slips in Second Gear .
    â€¢ Refer to No Third Gear, Slips in Third Gear .
    â€¢ Refer to No Fourth Gear, or Slips in Fourth Gear .

Shift Speed Diagnosis

This category contains the following topic:

Inaccurate or inconsistent shift points

Refer to Inaccurate/Inconsistent Shift Points .

Torque Converter Diagnosis

This category contains the following topics:

    â€¢ Torque Converter Diagnosis
    â€¢ TCC remains engaged
    â€¢ TCC application while engine is cold
    â€¢ TCC shudder
    â€¢ Engine stalling
    â€¢ Refer to Torque Converter Diagnosis .
    â€¢ Refer to No Torque Converter Clutch Release .
    â€¢ Refer to Torque Converter Clutch Shudder .
    â€¢ Refer to Engine Stall .

If no symptoms are found:

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