Pressure Regulating Solenoid: Description and Operation

PRESSURE CONTROL SOLENOID
The pressure control solenoid (ST) is located in the shift solenoid assembly which is fitted on the transmission. This solenoid controls the system pressure in the transmission.

Unlike the other solenoids the pressure control solenoid is not grounded in the transmission, but instead the solenoid's power circuit is switched on in the Transmission Control Module (TCM). The solenoid is powered via pin 16 in the TCM and the return feed goes to pin 34 in the TCM. The solenoid is controlled by varying current from the TCM. The current is primarily affected by the throttle position. When the current is high, about 1 A, the fluid pressure becomes low and when the current is low or switched off, the system pressure becomes maximum.

The winding resistance in the solenoid is about 4 ohms.

When idling, with the hand-brake applied and selector lever in position D, the current should be about 900 mA and the fluid pressure 3.4 - 4.6 bar.