GM Service Manual Online
For 1990-2009 cars only

Check

Causes

DEFINITION: A large engine RPM increase is noted in fourth gear or no vehicle forward speed increase. Shifts into fourth gear are soft or do not occur.

Control Valve Body Accumulator Assembly

    • 3-4 shift valve stuck applied
    • 3-4 shift control valve stuck released

Direct and Reverse Clutch

    • Damaged or worn piston (406)
    • Damaged or worn clutch plates
    • Damaged ball check valve (405)