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Hydraulic control system

Hydraulic control system


The hydraulic control system consists of an oil pump, valve housing with gear changing valves and an accumulator, together with clutches and brakes.

Depending on the pressure built up by the pump and the selector lever position, the hydraulic control system controls the hydraulic pressure that actuates the torque converter clutch and other clutches and brakes to suit the current type of driving.

There are 8 solenoid valves on the valve housing. Solenoids S1-S5 are activated when they are energized by the TCM. The solenoids control the gear change valves so that gear changing occurs. The TCM uses information about the input/output speeds of the transmission and the position of the accelerator pedal in order to determine the correct moment at which to change gear.

The SLU (Lock Up Linear Solenoid), the SLT (Throttle Linear Solenoid), and the SLS (Clutch Pressure Control Linear Solenoid) solenoids are controlled by a 300 Hz PWM signal from the TCM.

SLU controls the engagement and disengagement of the Lock-up.

SLT controls the system pressure of the transmission.

SLS accurately controls the oil pressure to the various clutches.

This design allows greater possibilities for controlling the gear change points and other functions because control is effected by means of the TCM software.