GM Service Manual Online
For 1990-2009 cars only

Checks

Cause

Line Pressure

    â€¢ Too high
    â€¢ Too low

Pressure Control Solenoid Valve (320)

    â€¢ Failed Off
    â€¢ Loose connector

PCM

Loose connector

Accumulator Piston

    â€¢ Leaking
    â€¢ Stuck

Accumulator Spring

Incorrect

Checkballs

Missing

Calibration PROM

Incorrect

Check the PCM for current DTCs.