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.

Shift solenoid 1 (SS1) is a normally closed (N/C) solenoid that provides control main pressure to stroke shift valve 1. The transmission control module (TCM) determines the proper solenoid command logic to move shift valve 1 to attain a particular range.

The TCM provides voltage to pressure control solenoid 2 (PCS2) and shift solenoid 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 SS1 ON and OFF.

Since the valve state, stroked or unstroked, is critical to providing the correct transmission range, the shift valve has a pressure switch, located in the pressure switch manifold, to provide feedback to the TCM about the position of the valve.

DTC P0973 is a type A DTC.