GM Service Manual Online
For 1990-2009 cars only

Transmission performance may be influenced by one, or more of the following items:

    â€¢ Fluid level high/low.
    â€¢ Engine performance.
    â€¢ Manual linkage adjustment.
    â€¢ Internal fluid leaks.
    â€¢ Electrical system.
    â€¢ Transmission or other mechanical component.
    â€¢ Vacuum Modulator System

These items should be checked and corrected, if necessary, before attempting transmission diagnosis.