GM Service Manual Online
For 1990-2009 cars only

Component

Inspect

Control Valve Body

    • The 1-2 Shift Valve is sticking
    • Spacer plate is incorrect, incorrectly assembled or damaged

Case

The case to valve body face is damaged or is not flat

Shift Solenoid Valves

    • Stuck or damaged
    • Faulty electrical connection

2-4 Servo Assembly

    • The apply passage case is restricted or blocked
    • Nicks or burrs on the servo pin or on the pin bore in the case
    • Fourth servo piston is installed backwards

2-4 Bank Assembly

    • The 2-4 band is worn or damaged
    • The band anchor pin is not engaged