Electronic-Hydraulic Control System

22. ELECTRONIC-HYDRAULIC CONTROL SYSTEM





General
The electronic-hydraulic control system consists of various sensors and switches, a Transmission Control Module (TCM) and the hydraulic controller including solenoid valves. The system controls the transmission proper including shift control, lock-up control, overrunning clutch control, line pressure control, auto pattern select control and shift timing control. It also controls the AWD transfer clutch. In other words, the system detects various operating conditions from various input signals and sends output signals to shift solenoids 1, 2 and 3 and duty solenoids A, B and C (a total of six solenoids).





Input Signal





Output Signal








Control Item

Throttle Position Sensor
The throttle position sensor provides electrical signals corresponding to the throttle position. The throttle position and accelerator depression speed are detected by this throttle position sensor output.





Vehicle Speed Sensor 1 Of FWD Model (Mounted Inside The Transmission)
The vehicle speed sensor 1 is mounted to the transmission case (at the rearside of the case). The sensor outputs a pulse signal which is transmitted to the TCM where it is converted to vehicle speed.
Vehicle speed sensor 1 on the FWD model detects front-wheel speed.





Vehicle Speed Sensor 1 Of AWD Model
The vehicle speed sensor 1 (output shaft rotation sensor) is mounted to the extension case (from the outside of the case). The sensor outputs a pulse signal which is transmitted to the TCM where it is converted to vehicle speed.
The transfer clutch drum is connected directly to the rear wheel driving propeller shaft. Vehicle speed sensor 1 on the AWD model detects rear-wheel speed.

Vehicle Speed Sensor 2 (Mounted With The Transmission)
The vehicle speed sensor (output shaft rotation sensor) is mounted to the torque converter clutch case (from the outside of the case). The sensor outputs a sine wave signal which is transmitted to the vehicle speed detection circuit in the combination meter where it is converted to vehicle speed.
Vehicle speed sensor 2 detects front-wheel speed.





ATF Temperature sensor
This sensor is mounted to the control valve in the transmission. It detects temperature change as an analog electrical signal. The output characteristics of the sensor are shown below.





Inhibitor Switch
The inhibitor switch assures safety when starting the engine. This switch is mounted on the right side of the transmission case, and is operated by the range selector lever.
When the selector lever is set to "P" or "N", the electrical circuit is connected in the inhibitor switch and the starter circuit is energized for cracking the engine.
When the selector lever is set to "R", "D", "3", "2", or " 1 " range, the electrical circuit is disconnected in the inhibitor switch. Hence engine cranking is disabled. In the "R" range, the backup light circuit is completed in the switch, and the backup lights come on.
In addition to the above function, the inhibitor switch incorporates a circuit for detecting the selected range position and sending the range signal to the TCM.





Sol. 1 (Shift) And Sol. 2 (Shift)
These solenoids are mounted to the control valve. They are turned ON or OFF according to signals sent from the TCM. The gear positions are changed according to the ON and OFF condition of these solenoids.

Sol. 3 (Overrunning Clutch)
This solenoid is also mounted to the control valve. It is turned ON or OFF according to the signal sent from the TCM. This operation controls the engagement and disengagement of the overrunning clutch.

Duty Sol. A (Line Pressure)
This solenoid is mounted to the control valve, and its duty ratio is controlled by the signal sent from TCM. This solenoid then controls the pressure modifier valve and pressure regulator valve to adjust the line pressure to an optimum pressure level suitable for operating conditions.

Duty Sol. B (Lock-Up)
This solenoid is mounted to the control valve, and its duty ratio is controlled by the signal sent from TCM. It then controls the lock-up control valve to provide smooth engagement and disengagement of the lock-up clutch.





Duty Sol. C (Transfer)
This solenoid is mounted to the transfer control valve on the side of extension case, and its duty ratio is controlled by the signal sent from TCM. It then controls the transfer control valve for controlling the transfer clutch hydraulic oil pressure.