GM Service Manual Online
For 1990-2009 cars only

Harsh Shift D4 to D3, D2, or D1 for Chevrolet Chevy MD Steel Tilt (W Model) 2002

Harsh Shifts -- Fourth to Third, Second, or First

Checks

Cause

Spring Assembly (506)

Not functioning

Checkball

Plugged

Snap Ring (511)

Not seated

Scan Tool Shift Adapts

Maximum shift adapts