Hydraulic Control System - Toyota 1991 Camry Repair Manual

AT-8

Hydraulic Control System

R A540E, A540H
The hydraulic control system is composed of the oil pump, the valve body, the solenoid valves, the accu-
mulators, the clutches and brakes, and the governor valve as well as the fluid passages which connect all
of these components.
Based on the hydraulic pressure created by the oil pump, the hydraulic control system governs the hy-
draulic pressure acting on the torque converter, clutches and brakes in accordance with the vehicle driving
conditions.
There are three solenoid valves on the valve body.
The No. 1 and No. 2 solenoid valves are turned on and off by signals from ECU to operate the shift valves
and change the gear shift position.
The No. 3 solenoid valve is operated by signals from the ECU to engage or disengage the lock-up clutch
of the torque converter.
R A540H
There are two center differential control solenoid valves on the transfer.
The solenoid valves are adjusting the center differential control pressure.
HYDRAULIC CONTROL SYSTEM
OIL PUMP
Throttle Cable
ECU
AUTOMATIC TRANSAXLE
VALVE BODY
Hydr. pressure control
Fluid passage switching
SOLENOID VALVES
- Operation
CLUTCHES & BRAKES Planetary gear unit
Torque converter