Electronic Control System

ELECTRONIC CONTROL SYSTEM [GF4A-EL]





Automatic Transaxle Block Diagram





EC-AT Operation Chart








Electronic Control Item and Control





Component Description (Electronic Control)





Automatic Transaxle Device Relationship Chart


Input/Turbine Speed Sensor Description





- A magnetic-pickup generator located in the upper part of the transaxle detects the reverse and forward drum speed (torque converter output speed).
- The generator is installed on the transaxle case with clearance to the reverse and forward drum.
- The reverse and forward drum has 32 projections in total at intervals 11° 15° end generates AC waveforms during rotation.
- When the reverse and forward drum rotates, an induced electromotive force is generated in the input/turbine speed sensor; AC waveforms are created, These waveforms are input into the PCM for waveform rectifying and decoding of the number of pulses.
- The reverse and forward drum generates 32 pulse signals per reverse and forward drum rotation.

Vehicle Speedometer Sensor Description





- A magnetic-pickup vehicle speedometer sensor built into the speedometer-driven gear detects the vehicle speed. 8 pulse signals are generated per turn of the speedometer-driven gear, and are sent to the PCM.
- The powertrain control module then receives the signals converted through the speedometer, and detects vehicle speed.
- If the vehicle speed pulse generator fails, the control module uses a signal from the vehicle speed sensor as a substitute.

Throttle Position Sensor, Idle Switch Description








- The throttle position sensor is a linear-type variable resistor attached to the throttle body. The throttle position sensor contains a plate that has contact points and is located coaxially with the throttle valve.
- This plate rotates together with the throttle valve, and the two contact points slide over the resistor printed on the base plate.
- As the plate rotates, voltage between the VREF terminal and the GND terminal increases in proportion to the rotation. The powertrain control module calculates the voltage ratio between terminals VREF and GND and terminals TVO and GND, and detects the throttle valve opening angle.
- The voltage ratio increases in proportion to the throttle valve opening angle. When the throttle valve is fully closed, the circuit between terminals IDLE and GND is linked by the idle switch, which detects the idle condition.

TR Switch Description
- The TR switch is installed in the upper part of the transaxle and detects the selector lever positions in park/neutral position, R,D,2, and 1 ranges.
- When the selector lever is in park/neutral position, R,D,2, or 1 range, each respective range switch is turned ON.

O/D OFF Switch Description
- A momentary type O/D OFF switch is attached to the selector lever knob.
- It has no difference in switching positions. O/D OFF mode can be selected by turning the O/D OFF switch ON and OFF.
- As a safeguard, the O/D OFF mode is canceled when the ignition switch is turned OFF. The O/D OFF switch turns ON/OFF by the O/D OFF switch internal circuit.
- The PCM detects the internal circuit switching and selects O/D OFF mode.

Brake Switch Description
- The brake switch is a push-type installed in the upper part of the brake pedal, and detects brake pedal application.
- When the brake pedal is depressed during TCC, the PCM releases TCC operation for smooth deceleration.

Cruise Control Module (4 GR Inhibit Signal) Description
- It sends signals to the PCM during cruise control operation when the RESUME switch is activated, the ACCEL switch is activated, or when the vehicle speed decreases 8 km/h (5 mph) below the set vehicle speed.

TFT Sensor Description





- The TFT sensor is located on the valve body. It sends a signal to the PCM which interprets voltage signals as ATF temperature.

Shift solenoid A, B, C
- Shift solenoid A, B. C control the line pressure applied to the 1-2, 2-3, 3-4 shift valves.
- The shift solenoid are switched ON and OFF by electric signals from the powertrain control module.

TCC control solenoid valve
- The TCC control solenoid valve controls the line pressure applied to the TCC shift valve. The solenoid valve is switched ON and OFF by electric signals from the powertrain control module.

3-2 timing solenoid valve
- The 3-2 timing solenoid valve controls the line pressure applied to the 3-2 timing valve. The solenoid valve is switched ON and OFF by electric signals from the powertrain control module.

Pressure control solenoid
- The pressure control solenoid regulates modifier pressure to control line pressure.
- The duty-cycle pressure control solenoid freely controls the ratio of ON time in one cycle from 0 to 100%. It repeats ON and OFF at a frequency of 31.25 Hz (0.032 second per cycle), and opens and closes the drain port to control modifier pressure at a specified level.
- Therefore, modifier pressure increases when the duty ratio (ratio of 31.25 Hz ON time) decreases. Conversely, modifier pressure decreases when the duty ratio increases.
- When the solenoid valve is OFF, hydraulic pressure applied to the valve is retained. The pressure applied to the valve overcomes the spring force and the valve moves to the left.
- When the solenoid valve is ON, pressure applied to the valve is drained and the valve moves to the right side by spring force.
- This valve switches the hydraulic pressure lines and controls the operation of the each component.








Operation