Park Mode
WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
While the transmission is in Park with the engine idling, Fast Learn will cycle through a series of tests where C3 and C4 clutches are repeatedly applied to learn their clutch characteristics. During the C3 and C4 clutch apply/release procedure, Fast Learn is able to characterize the "A" and "B" solenoid pressures corresponding to clutch return springs, and also is able to learn the volumes for C3 and C4 clutch packs. In addition, C5 clutch is repeatedly applied and released in Park to purge out air for later learning of its clutch volume.