Circuit 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 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 for reverse pressure. Fluid pressure is supplied to the pressure switch 4 (PS4) when the manual selector valve is in any position except REVERSE. When the manual selector valve is moved to REVERSE, pressure to PS4 is cut off, causing the switch to close.
DTC P0878 is a type B DTC.