A/T

A: GENERAL
The electrohydraulic control system for the transmission and transfer consists of various sensors and switches, a Transmission Control Module (TCM) and the hydraulic controlling units including solenoid valves. The system controls the automatic transmission operation, including gear shifting, lock-up clutch operation, line pressure, automatic control pattern selection ("Base" and "Power"), and gear-shift timing. It also controls the operation of the transfer clutch. The TCM determines vehicle operating conditions from various input signals and controls a total of eight solenoids (shift solenoids 1 and 2, low clutch timing solenoid, 2-4 brake timing solenoid, line pressure duty solenoid, lock-up duty solenoid, transfer duty solenoid, and 2-4 brake duty solenoid) by sending appropriate signals to them.





B: INPUT SIGNALS





C: OUTPUT SIGNALS





D: CONTROL ITEMS





E: THROTTLE POSITION SENSOR
The throttle position sensor provides electrical signals corresponding to throttle valve positions. The throttle valve angular position and accelerator depressing speed are detected by this throttle position sensor.

F: REAR VEHICLE SPEED SENSOR





This rear vehicle speed sensor (output shaft speed sensor) is externally mounted on the extension case. It detects the rear wheel speed in terms of the peripheral speed of the transfer clutch drum and sends sine wave signals (30 pulses per rotation) to the TCM.

G: FRONT VEHICLE SPEED SENSOR





This front vehicle speed sensor (output shaft speed sensor) is externally mounted on the transmission case. It detects the front wheel speed and sends sine wave signals (16 pulses per rotation) to the TCM.
The TCM converts the signals into pulse signals and outputs them to both the Engine Control Module (ECM) and the combination meter.

H: ATF TEMPERATURE SENSOR





This sensor is located in the hydraulic control valve of the transmission. It detects the temperature of ATF and outputs it as an electrical resistance signal. The output characteristics of the sensor are shown.

I: TORQUE CONVERTER TURBINE SPEED SENSOR





The torque converter turbine speed sensor (output shaft speed sensor) is externally mounted on the transmission case.
The sensor detects the torque converter turbine speed in terms of the rotation speed of the periphery of the high clutch drum coupled to the input shaft, and sends sine wave signals (32 pulses per rotation) to the TCM. The TCM calculates the proportion of the input shaft speed to the vehicle speed and determines whether the shifting is to be made or not.

J: 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 selector lever.
When the selector lever is set to P or N. the electrical circuit in the inhibitor switch is closed and the starter circuit is completed for cranking the engine.
When the selector lever is in the R, D, 3, 2 or 1 range, the electrical circuit in the inhibitor switch is open. 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.

K: SHIFT SOLENOIDS 1 AND 2





These solenoids are located in the transmission hydraulic control valve. They are turned ON or OFF according to signals from the TCM. The gear positions are changed according to the ON and OFF condition of these solenoids.

L: LOW CLUTCH TIMING SOLENOID





This solenoid is located in the transmission hydraulic control valve. It is turned ON or OFF according to signals from the TCM. It then controls the low clutch timing valve B and reverse inhibitor valve.

M: 2-4 BRAKE TIMING SOLENOID





This solenoid is located in the transmission hydraulic control valve. It is turned ON or OFF according to signals from the TCM. It then controls the 2-4 brake timing valve B to decrease the change gear shock.

N: LINE PRESSURE DUTY SOLENOID





This solenoid is located in the transmission hydraulic control valve. Its duty ratio is controlled by signals from the TCM. This solenoid then controls the pressure modifier valve and accumulator control valve A to adjust the line pressure to an optimum pressure level suitable for operating conditions.

O: LOCK-UP DUTY SOLENOID





This solenoid is located in the transmission hydraulic control valve. Its duty ratio is controlled by signals from the TCM. It then controls the lock-up control valve to provide smooth engagement and disengagement of the lock-up clutch.

P: 2-4 BRAKE DUTY SOLENOID





This solenoid is located in the transmission hydraulic control valve. Its duty ratio is controlled by signals from the TCM. It modulates the 2-4 brake pressure when the 2-4 brake is operated, reducing shifting shocks.

Q: TRANSFER DUTY SOLENOID





This solenoid is located in the transfer hydraulic pressure control unit on the rear end of transmission case. Its duty ratio is controlled by signals from the TCM. It then controls the transfer clutch/ control valve to control the pressure applied to the transfer clutch.