Pressure Regulation

WARNING: This page is about a different car, the 2007 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.

Manual Valve

The gear selector lever mechanically moves the manual valve. While this is occurring, the valve directs line pressure through the PRND4 fluid passage into the reverse circuit. Reverse fluid then routes to the pressure regulator valve and to the reverse orifice bypass valve. Reverse fluid then passes through orifice #6. The fluid seats checkball #7 before routing to the 1-2 shift valve.

Internal Mode Switch (IMS)

The internal mode switch (IMS) is a sliding contact electrical switch assembly that corresponds to the PRNDL position selected. Each of the PRNDL positions has a unique ground pattern on the five wires from the TCM. The IMS consists of two major components: The housing, which houses the tracks and makes up the stationary contacts. The Insulator assembly makes up the moving contacts and is linked to the detent lever. The range detection is accomplished by securing the moving contacts of the IMS to the detent lever. When the driver selects a PRNDL position, the detent lever inside the transaxle rotates. This slides the IMS moving contacts which in return grounds the five wires in a unique pattern for each gear selection corresponding to the PRNDL position selected. The IMS is electrically connected by six wires (four of which the TCM supplies voltage to and one wire that is a common ground and one wire is connected directly to the ECM) to the transaxle pass through connector.

Pressure Regulator Valve

Reverse fluid pressure combines with torque signal fluid to increase hydraulic pressure in the line circuit. A change to the vehicle operating conditions produces changes in the throttle position. The changes to the throttle position influence fluctuations in line pressure.