Circuit/System Description
WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The clutch pressure control (PC) solenoid 2 flows fluid to the 3-5-R clutch when commanded off and exhausts fluid when commanded on. The clutch PC solenoid 2 regulates the transmission fluid pressure to the 3-5-R clutch. The transmission fluid pressure (TFP) switch 1 opens (high) under fluid pressure and closes (low) when no pressure is present. The transmission control module (TCM) calculates gear ratio based on data from the automatic transmission input speed sensor (ISS) and the output speed sensor (OSS). The TCM compares the known transmission gear ratio to a calculated gear ratio for each commanded gear.