GM Service Manual Online
For 1990-2009 cars only

Inaccurate Shift Points

Checks

Causes

Oil Pump Assembly

    â€¢ Stuck pressure regulator valve.
    â€¢ Sticking pump slide.

Valve Body Assembly

Spacer plate or gaskets misassembled, damaged or incorrect

Case

    â€¢ Porous or damaged valve body pad.
    â€¢ 2-4 Servo Assembly.
       - 2-4 accumulator porosity
       - Damaged servo piston seals.
       - Apply pin damaged or improper length.
    â€¢ 2-4 Band Assembly.
       - Burned
       - Anchor pin not engaged.

Throttle Position Sensor

    â€¢ Disconnected
    â€¢ Damage

Vehicle Speed Sensor

    â€¢ Disconnected
    â€¢ Damaged
    â€¢ Bolt not tightened

4WD Low Switch

    â€¢ Disconnected
    â€¢ Damaged.