GM Service Manual Online
For 1990-2009 cars only

Checks

Causes

1-2 Shift Solenoid Valve

Debris, stuck

3-4 Shift Valve

Debris, stuck

Coast Clutch Plates

Burned or damaged

Coast Clutch Seal/Checkball

Cut, worn or nicked

Fluid Level

    â€¢ Low
    â€¢ Stuck in upshift position

Forward Clutch Housing

    â€¢ Splines damaged
    â€¢ Housing cracked