Circuit Description

WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The pressure switch manifold is a multiple-switch assembly made up of three normally open and one normally closed pressure switches. Fluid pressure is fed from shift valve "E" to the switch based on the position of the valve. The shift valve fluid pressure reflects the logic condition at the corresponding solenoid. This logic indicates the current transmission operating range to the Transmission Control Module (TCM).

The fluid pressure switch corresponding to the shift valve is normally open (contacts not touching) when no fluid pressure is present, so that electrical current is stopped at the switch. When fluid pressure is routed to the switch, it moves the diaphragm and upper contact so that the contact element touches both the positive and ground contacts. This closes the circuit and allows current to flow from the positive contact and through the switch. The pressure switch corresponding to Reverse is normally closed, since fluid pressure is always present unless the selector valve is moved to Reverse.

This is a type "A" DTC.