GM Service Manual Online
For 1990-2009 cars only

Check

Causes

DEFINITION: A large engine RPM 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

    â€¢ 3-4 shift valve stuck applied
    â€¢ 3-4 shift control valve stuck applied

Direct and Reverse Clutch

    â€¢ Damaged or worn piston (406)
    â€¢ Damaged or worn clutch plates
    â€¢ Damaged ball check valve (405)