Engine Control

System Outline

The engine control system utilizes a microcomputer and maintains overall control of the engine, transmission 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. Vehicle speed signal circuit
The vehicle speed signal is input from the ABS speed sensor to skid control ECU, and are sent to the hybrid vehicle control ECU through communication control.

4. RPM signal circuit
Camshaft position is detected by the VVT sensors and its signal is input to TERMINALS VV1+ and VV2+ of the hybrid vehicle control ECU as a control signal. Also, engine RPM is detected by the crankshaft position sensor and is input as a control signal to TERMINAL NE+.

5. Throttle position signal circuit
The throttle control motor and 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. 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 +B1 and +B2 of the hybrid vehicle control ECU through the IGCT NO.2 fuse.

7. Intake air volume signal circuit
Intake air volume is detected by the mass air flow meter and the signal is input to TERMINAL VG of the hybrid vehicle control ECU as a control signal.

8. Stop light SW signal circuit
The stop light 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 sensors and the signal is input into TERMINALS KNK1 and KNK2 as a control signal.

10. Air fuel ration signal circuit
The air fuel ration is detected and input as a control signal into TERMINALS A1A+ and A2A+ of the hybrid vehicle control ECU.

11. Oxygen sensor signal circuit
The oxygen density in the exhaust gases is detected and input as a control signal into TERMINALS OX1B and OX2B of the hybrid vehicle control ECU.
To maintain stable detection performance by the heated oxygen sensor, a heater is used for warning the sensor. The heater is also controlled by the hybrid vehicle control ECU (HT1B and HT2B).

12. Fuel cut in a collision
The system receives the collision signal from airbag sensor assembly in the vehicle has a collision and stops the fuel pump operation on the side 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 (Input signals from (1) to (11) etc.) to the hybrid vehicle control ECU. And the control signal is output to TERMINALS #10, #20, #30, #40, #50 and #60 of the hybrid vehicle control ECU to operate the 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 (Input signals from (1) to (11) etc.). 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, IGT5 and IGT6. This signal controls the igniter to provide the best ignition timing for the driving conditions.

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.