GM Service Manual Online
For 1990-2009 cars only

Check

Causes

DEFINITION: A large engine RPM increase and forward vehicle speed decrease in third gear do not immediately occur when the transmission is shifted from overdrive or fourth gear in Drive or Manual Third range to third gear range.

Overdrive Clutch

    • Damaged or cut piston
    • Damaged or worn clutch plates

Control Valve Body Accumulator Assembly

    • 3-4 shift valve and/or 3-4 control shift valve stuck released
    • Low pressure control valve stuck released
    • 4-5 shift valve and/or 4-5 control shift valve stuck released
    • 1-2 shift valve stuck applied
    • 2-3 shift and/or 2-3 control shift stuck applied