Fluid Pressure Sensor/Switch: Description and Operation

PRESSURE CONTROL (PC) SOLENOID VALVE





The Pressure Control (PC) solenoid valve is a precision electronic pressure regulator that controls transaxle line pressure based on current flow through its coil windings. As current flow is increased the magnetic field produced by the coil moves the solenoid's plunger further away from the exhaust port. Opening the exhaust port decreases the output fluid pressure regulated by the PC solenoid valve, which ultimately decreases line pressure. The PCM controls the PC solenoid valve based on various inputs including throttle position, fluid temperature, MAP sensor and gear state.
The PCM controls the PC solenoid valve on a positive duty cycle at a fixed frequency of 614 Hz (cycles per second). Duty cycle is defined as the percent of time current is flowing through the solenoid coil during each cycle. A higher duty cycle provides a greater current flow through the solenoid. The high (positive) side of the PC solenoid valve electrical circuit at the PCM controls the PC solenoid valve operation. The PCM provides a ground path for the circuit, monitors average current and continuously varies the PC solenoid valve duty cycle to maintain the correct average current flowing through the PC solenoid valve.

Duty Cycle Current Line Pressure
+5% 0.02 amps Maximum
+40% 1.1 amps Minimum

Pressure control solenoid valve resistance should measure between 3.5 and 4.6 ohms when measured at 68°F (20°C).