Circuit/System Description

WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The pressure switch manifold (PSM) is a multiple switch assembly made up of 3 normally open (N/O) pressure switches and 1 normally closed (N/C) pressure switch. Pressure switch 1 (PS1) monitors shift valve 1 positioning, pressure switch 2 (PS2) monitors shift valve 2 positioning, pressure switch 3 (PS3) monitors shift valve 3 positioning, and pressure switch 4 (PS4) monitors the position of the manual selector valve. The pressure switches communicate the positioning to the transmission control module (TCM). The position of the shift valves 1, 2, and 3 is controlled by 3 normally solenoids, shift solenoid 1 (SS1), shift solenoid 2 (SS2), and shift solenoid 3 (SS3). When energized, SS1 directs control main pressure to shift valve 1, SS2 directs control main pressure to shift valve 2, and SS3 directs control main pressure to shift valve 3, which strokes the shift valves. When the valve is stroked, an exhaust passage is blocked and fluid pressure to normally open PS1, PS2, or PS3 increases. The TCM provides a signal circuit to PS1, PS2, and PS3. The low reference to the switches is provided through the metal base of the PSM which is connected to chassis ground through the transmission case.