GM Service Manual Online
For 1990-2009 cars only

No Overrun Braking - Manual 3-2-1

Checks

Causes

External Linkage

Not adjusted properly

Valve Body Assembly (60)

    â€¢ 4-3 Sequence valve stuck
    â€¢ Checkball mispositioned
    â€¢ Spacer plate and gaskets incorrect, damaged or mispositioned

Overrun and Forward Clutch Assembly (644-651)

    â€¢ Turbine shaft oil passages plugged or not drilled
    â€¢ Turbine shaft seal rings damaged
    â€¢ Turbine shaft sealing balls loose or missing
    â€¢ Porosity in forward or overrun clutch piston
    â€¢ Overrun piston seals cut or damaged
    â€¢ Overrun piston checkball not sealing