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 closed shift solenoids. When energized, SS1 directs fluid pressure to shift valve 1, SS2 directs fluid pressure to shift valve 2, and SS3 directs fluid pressure to shift valve 3, which strokes the shift valves. When the shift valve is stroked, an exhaust passage is blocked and fluid pressure to the normally open PS1, PS2, or PS3 increases. When the selector valve is in neutral or any forward position, an exhaust passage is blocked and fluid pressure to the normally closed PS4 increases.