Circuit Description
WARNING: This page is about a different car, the 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, 2002 Chevrolet Silverado, and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Shift solenoid "D" is a normally closed solenoid that provides the necessary logic to distribute fluid to the correct clutches. The shift solenoid provides either full pressure or exhaust to the head of shift valve "D". Since the valve state, stroked or unstroked, is critical to providing the correct transmission gear range, the shift valve has a pressure switch (located in the pressure switch manifold) which provides feedback to the computer as to the valve's position.
This is a type "A" DTC.