Transmission Control Systems: Description and Operation

System Outline

Hybrid System
The hybrid system is a power train to combine and use two different kinds of power sources such as gasoline engine and electric motor. The system uses optimum power source, either the gasoline engine or electric motor to fit the driving condition best and maximizes each one s strengths while compensating for each other's shortcomings. Thus, the driving performance with seamless response is attained and the fuel consumption and gas emission are reduced significantly at the same time.

Shift Control System
Park/Neutral position SW is provided in the transaxle to detect the shift position and send a corresponding signal to the hybrid vehicle control ECU. Upon receiving this signal, the hybrid vehicle control ECU optimally combines the operation of the engine, motor generator no.1 (Front), motor generator no.2 (Front) and motor generator (Rear), in order to produce the respective shift position ("R","N","D" and "B" ).

Engine Control System
The engine control system utilizes a microcomputer and maintains overall control of the engine, transaxle etc. An outline of the engine control is given here.

1. Input Signals
1. Engine coolant temp. signal circuit
The engine coolant temp. sensor detects the engine coolant temp. and has a built in thermistor with a resistance, which varies according to the engine coolant temp.. The engine coolant temp. which is input into TERMINAL THW of the hybrid vehicle control ECU as a control signal.

2. Intake air temp. signal circuit
The intake air temp. sensor is installed in the mass air flow meter and detects the intake air temp. which is input as a control signal to TERMINAL THA of the hybrid vehicle control ECU.

3. Oxygen density signal circuit
The oxygen density in the exhaust emission is detected by the heated oxygen sensor and input as a control signal to TERMINAL OX1B of the hybrid vehicle control ECU.

4. RPM signal circuit
Camshaft position and crankshaft position are detected by the camshaft position sensor and crankshaft position sensor. Camshaft position is input as a control signal to TERMINAL G2+ of the hybrid vehicle control ECU, and engine RPM is input into TERMINAL NE+.

5. Throttle position signal circuit
The throttle position sensor detects the throttle valve opening angle as a control signal, which is input into TERMINALS VTA1 and VTA2 of the hybrid vehicle control ECU.

6. Vehicle speed circuit
The vehicle speed sensor, detects the vehicle speed and input to speed sensor of the skid control ECU, from skid control ECU to TERMINAL SPD of the hybrid vehicle control ECU, Via combination meter.

7. Battery signal circuit
Voltage is constantly applied to TERMINAL BATT of the hybrid vehicle control ECU. With the ignition SW turned on, the voltage for hybrid vehicle control ECU start up power supply is applied to TERMINALS +B and +B2 of the hybrid vehicle control ECU via the EFI relay.

8. Stop lamp SW signal circuit
The stop lamp SW is used to detect whether the vehicle is braking or not and the signal is input into TERMINAL STP of the hybrid vehicle control ECU as a control signal.

9. Engine knock signal circuit
Engine knocking is detected by knock sensor and the signal is input into TERMINAL KNK1 as a control signal.

10. Air fuel ratio signal system
The air fuel ratio is detected and input as a control signal into TERMINAL A1A+ of the hybrid vehicle control ECU.

2. Control System
- SFI system
The SFI system monitors the engine condition through the signals input from each sensor to the hybrid vehicle control ECU. And the control signal is output to TERMINALS #10, #20, #30, #40 of the hybrid vehicle control ECU to operate the fuel injector (Inject the fuel). The SFI system controls the fuel injection operation by the hybrid vehicle control ECU in response to the driving conditions.

- ESA system
The ESA system monitors the engine condition through the signals input to the hybrid vehicle control ECU from each sensor. The best ignition timing is decided according to this data and the memorized data in the hybrid vehicle control ECU and the control signal is output to TERMINALS IGT1, IGT2, IGT3, IGT4. This signal controls the igniter to provide the best ignition timing for the driving conditions.

- Heated oxygen sensor heater control system
The heated oxygen sensor heater control system turns the heater on when the intake air volume is low (Temp. of exhaust emissions is low), and warms up the heated oxygen sensor to improve detection performance of the sensor. The hybrid vehicle control ECU evaluates the signals from each sensor, and outputs current to TERMINAL HT1B to control the heater.

3. Diagnosis System
With the diagnosis system, when there is a malfunction in the hybrid vehicle control ECU signal system, the malfunctioning system is recorded in the memory. The malfunctioning system can be found by reading the code displayed by the malfunction indicator lamp.

4. Fail-Safe System
When a malfunction has occurred in any system, if there is a possibility of engine trouble being caused by continued control based on the signals from that system, the fail-safe system either controls the system by using data (Standard values) recorded in the hybrid vehicle control ECU memory or else stops the engine.

Cruise Control System
The cruise control system is a constant vehicle speed controller which controls the opening angle of the engine throttle valve by the SW, and allows driving at a constant speed without depressing the accelerator pedal.

1. Set Operation
When the ON-OFF SW is turned on, the systems starts preparations for cruise control and turns on the indicator light in the combination meter.

2. Set Speed Control
When the -SET SW is operated with the ON-OFF SW turned on during driving, the speed is controlled at a constant speed.

3. Coast Control
When the -SET SW is kept turned on during cruise control driving, the hybrid vehicle control ECU controls the throttle valve to decelerate the vehicle speed.
Every time the SET SW is turned on instantaneously, the vehicle speed is decelerated by approx. 1.6 km/h.

4. Accel Control
When the + RES SW is kept turned on during cruise control driving, the hybrid vehicle control ECU controls the throttle valve to accelerate the vehicle speed.
Every time the + RES SW is turned on instantaneously, the vehicle speed is accelerated by approx. 1.6 km/h.

5. Resume Control
If the vehicle speed is within the low speed limit (Approx. 40 km/h, 25 mph) when canceling the cruise control, operation of the + RES SW accelerates the vehicle speed and resumes the level before canceling the cruise control.

6. Manual Cancel Mechanism
If any one of the following signals is input during cruise control driving, the cruise control is canceled.
- The stop light SW is on
- The CANCEL SW is turned on
- The ON-OFF SW is turned off
- Gear is shifted D position to other positions than D.

7. Auto Cancel Function
If any of the following conditions are detected, the cruise control is canceled:
- Failure in the stop light SW wiring
- Abnormality in the vehicle speed signal
- Malfunction in the electronically controlled throttle parts
- When the vehicle speed gets slower than the low speed limit.
- When the vehicle speed falls to 16 km/h less than the set speed.