Circuit/System Description
WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Shift solenoid 3 (SS3) is a normally closed (N/C) solenoid that provides control main pressure to stroke shift valve 3. The transmission control module (TCM) determines the proper solenoid command logic to move shift valve 3 to attain a particular range. The TCM provides B+ to pressure control solenoid 2 (PCS2), and shift solenoids 1, 2, and 3 (SS1, SS2, and SS3) through a separate solid state device called high side driver 2 (HSD2). The TCM uses a low side driver to switch SS3 ON and OFF. Since the shift valve position is critical in determining the correct transmission range, a pressure switch located in the pressure switch manifold provides feedback to the TCM on the position of the valve.