GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1999 🢒 Eldorado 🢒 Transmission/Transaxle 🢒 Automatic Transaxle - 4T80-E 🢒 Symptom Diagnosis

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.

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 Fluid Foaming .
    • Refer to Converter Ballooning .
    • Refer to Low Line Pressure .
    • Refer to Fluid Leak Diagnosis .
    • Refer to Leak at Bottom Pan .
    • Refer to Leak at Fluid Fill Indicator .
    • Refer to Leak at Vehicle Speed Sensor .
    • Refer to Leak at Electrical Connector .
    • Refer to Leak at Cooler Connectors .
    • Refer to Leak at Case Extension .
    • Refer to Leak at Manual Shift .
    • Refer to Leak at Converter Seal .
    • Refer to Leak at Drive Axle Seal .

Noise and Vibration Diagnosis

This category contains the following topics:

    • Noise (drive gear, final drive, whine, growl, rattle, buzz, popping)
    • Vibration
    • Refer to Noise .
    • Refer to Noise in All Ranges .
    • Refer to Popping Noise .
    • Refer to Final Drive Noise or Hum Noise .
    • Refer to Vibration Diagnosis .

Range Performance Diagnosis

This category contains the following topics:

    • Drives in Neutral
    • No Park
    • No Reverse
    • No Drive
    • Loss of power
    • Stalling
    • No engine braking
    • No or incorrect gear selection
    • Starts in gear
    • Refer to Forward Motion in N .
    • Refer to Does Not Stay in Park .
    • Refer to No Reverse .
    • Refer to Transmission Slips in Reverse .
    • Refer to Loss of Drive .
    • Refer to Loss of Power .
    • Refer to No Torque Multiplication .
    • Refer to Engine Stall .
    • Refer to No Engine Braking .
    • Refer to No Overrun Braking in D3 .
    • Refer to No Overrun Braking in D2 .
    • Refer to No Engine Braking in D1 .
    • Refer to No Gear Selection .
    • Refer to Shift Lever Indicates Wrong Gear .
    • Refer to Engine Starts in Gear .

Shift Quality (Feel) Diagnosis

This category contains the following topics:

    • Harsh shifts
    • Soft Shifts
    • Refer to Harsh Shifts .
    • Refer to Soft Shifts .

Shift Pattern

This category contains the following topics:

    • Missing Gears
    • One forward gear only
    • Specific forward gears only
    • Slipping
    • Non-First Gear Starts
    • Refer to No First Gear .
    • Refer to No First Gear D2, D3, D4 .
    • Refer to No Second Gear D2, D3 .
    • Refer to No Third Gear - D3 .
    • Refer to No Fourth Gear .
    • Refer to Third and Fourth Gears Only .
    • Refer to Second Gear Starts .

Shift Speed Diagnosis

This category contains the following topics:

    • Inaccurate or inconsistent shift points
    • High shift speed
    • Refer to Inconsistent Shifts .
    • Refer to Extended or Delayed Upshifts .

Torque Converter Diagnosis

This category contains the following topics:

    • Torque Converter Diagnosis
    • TCC shudder
    • No TCC Apply
    • TCC remains engaged
    • Soft TCC Apply
    • Early TCC Apply
    • Engine stalls
    • Refer to Torque Converter Diagnosis .
    • Refer to No Torque Converter Clutch Apply .
    • Refer to Soft Torque Converter Clutch Apply .
    • Refer to Engine Stall .