ELECTRONIC CONTROL SYSTEM The electronic control system, which controls the shift points and the operation of the lock-up clutch, is composed of the following three parts: 1. Sensors These sensors sense the vehicle speed, throttle opening and other conditions and send this data to the ECU in the form of electrical signals. 2. ECU The ECU determines the shift and lock-up timing based upon the signals from sensors, and controls the solenoid valves of the hydraulic control unit accordingly. 3. Actuators These are three solenoid valves that control hydraulic pressure acting on the hydraulic valves to control shifting and lock up timing. SENSORS DRIVING PATTERN SELECTOR NEUTRAL START SWITCH THROTTLE POSITION SENSOR VEHICLE SPEED SENSOR BRAKE LIGHT SWITCH O/D MAIN SWITCH CRUISE CONTROL COMPUTER WATER TEMPERATURE SENSOR ECU Engine ECU Control of shift timing Control of lock-up timing Self-diagnostic system Back-up system ACTUATORS NO. 1 SOLENOID VALVE NO. 2 SOLENOID VALVE LOCK-UP SOLENOID VALVE O/D OFF INDICATOR LIGHT