GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2009 🢒 Lucerne 🢒 Transmission 🢒 Automatic Transmission - 4T80-E 🢒 Symptoms - Automatic Transmission

The following table consists of nine 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.

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 Automatic Transmission Fluid Leaks .

Noise and Vibration Diagnosis

This category contains the following topics:

    • Noise, drive gear, final drive, whine, growl, rattle, buzz, popping
    • Vibration
    • 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 .

Indicator On or Message Center Displays Message

This category contains the following topics:

    • Message Center displays "Trans Hot...Idle Engine"
    • Message Center displays "Change Trans Fluid"
    • Message Center displays "Service Transmission"
    • Refer to Transmission Fluid Check .
    • Refer to Fluid Foaming .
    • Refer to Diagnostic System Check - Vehicle .

If No Symptom Found
    • Refer to Transmission Fluid Check .
    • Refer to Road Test .
    • Refer to Line Pressure Check .