Hydraulic Controls

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 manual valve is mechanically controlled through the gear selector lever. The valve directs line pressure from the pressure regulator valve to the pressure switches and also into the PRN, the PRND4 and the PRND43 circuits.

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 (five of which the TCM supplies voltage to and one wire that is a common ground) to the transaxle pass through connector.

Pressure Control (PC) Solenoid Valve Feed Filter

The PC solenoid valve feed filter is located in the valve body. This device filters the actuator feed fluid before the fluid is routed to the PC solenoid valve.

Pressure Control (PC) Solenoid Valve

The Pressure Control (PC) Solenoid Valve is controlled by the PCM. This valve regulates the filtered actuator feed pressure which enters the torque signal circuit. Torque signal fluid is then routed to the pressure regulator valve, the 1-2 & 3-4 accumulator valve, and the 2-3 accumulator valve.

The 1-2 Shift Solenoid (SS) Valve

The 1-2 SS valve is energized (turned ON) by the PCM, blocking the exhaust port through the solenoid. This creates high pressure in the 1-2 shift solenoid valve circuit. Solenoid pressure holds the 1-2 shift valve in the downshifted position. This pressure is also routed to the 3-4 shift valve.

The 2-3 Shift Solenoid (SS) Valve

The 2-3 SS valve is de-energized (turned OFF) by the PCM, which allows fluid in the solenoid valve circuit to exhaust. Filtered actuator feed enters the solenoid valve circuit through orifice #16. This feed exhausts though the solenoid valve.

The 1-2 Shift Valve

High pressure from the 1-2 SS valve holds this valve in the downshifted position. PRN fluid passes between two valve lands and enters the Low & Reverse band apply fluid passage.

The 3-4 Shift Valve

Fluid from the 1-2 SS valve is routed to the end of the 3-4 shift valve against spring force, holding it in an upshifted position.

#6 Checkball (Low/Reverse Band Apply/Reduce)

This checkball is located in the valve body. The checkball seats against the Low & Reverse band reduce passage and routes fluid to the Low & Reverse servo piston.