Circuit/System Description

The pressure control (PC) solenoid valve is an electronic device located in the valve body. The transmission control module (TCM) controls transmission line pressure by regulating the current flow through the PC solenoid valve windings. The TCM determines the appropriate line pressure for a given load by monitoring the throttle position sensor voltage, the engine speed and other inputs. The TCM then varies the duty cycle on the high side of the PC solenoid valve to control current flow to the solenoid. The magnetic field produced by the coil moves the solenoid's internal valve which varies pressure to the pressure regulator valve. The TCM controls the PC solenoid valve by applying a varying amount of amperage to the solenoid. The applied amperage can vary from 0.1-1.1 amps. Low amperage, 0.1 amp, indicates high line pressure. High amperage, 1.1 amps, indicates low line pressure. The duty cycle of the PC solenoid valve is expressed as a percentage of energized ON time. Zero percent indicates zero ON time, non-energized, or no current flow. Approximately 60 percent at idle indicates maximum ON time, energized, or high current flow. Current is controlled from about 0.02 amp for maximum line pressure to 1.1 amps for minimum line pressure. The TCM monitors the actual current to the solenoid as compared to the requested or reference current.