Transmission Fluid Pressure (TFP) Manual Valve Position Switch
WARNING: This page does not describe the selected car, but rather 13 other vehicles, including the 2006 Saturn Relay, 2006 Pontiac Montana SV6, 2006 Pontiac Grand Prix, 2006 Pontiac G6, and 2006 Chevrolet Uplander. However, it is still accessible from the selected car via links, so may be relevant.
Release fluid pressure routed to the TFP manual valve position switch signals the PCM that the TCC is released.