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Hydraulic control system

Hydraulic control system


The hydraulic control system consists of an oil pump, valve housing with shifting valves and accumulators, 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 in the valve housing. Solenoid valves S1 - S5 are activated when supplied with current from the TCM. The solenoids control the shifting valves so that gearchanges take place. The TCM uses information on the input and output speeds of the transmission and the position of the accelerator to change gears at the correct moment.

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

SLU controls the engagement and disengagement of lock-up.

SLT controls the system pressure of the transmission.

SLS accurately controls the fluid pressure to the clutches.

This design provides great flexibility for controlling when gearchanges are made and other functions since control is provided by the software in the TCM.