GM Service Manual Online
For 1990-2009 cars only

Harsh Shifts

Checks

Cause

Line Pressure

    • Too high
    • Too low

Pressure Control Solenoid Valve (320)

    • Failed Off
    • Loose connector

VCM/PCM

Loose connector

Accumulator Piston

    • Leaking
    • Stuck

Accumulator Spring

Incorrect

Checkballs

Missing

Calibration PROM

Incorrect

Check the VCM/PCM for current DTCs