GM Service Manual Online
For 1990-2009 cars only

1-2 Shift Speed - High or Low

Checks

Cause

Possible Diagnostic Trouble Code Set

    â€¢ Refer to the Shift Speed Chart
    â€¢ Check service bulletins
    â€¢ Incorrect tooth count on VS Sensor Rotor
    â€¢ Wrong PROM
    â€¢ Wrong final drive ratio or model

Possible Diagnostic Trouble Code Set

    â€¢ Refer to Shift Seed Chart
    â€¢ Wrong PROM
    â€¢ Check Service Bulletins

Possible Diagnostic Trouble Code Set

    â€¢ Refer to Shift Speed Chart
    â€¢ Check service bulletins