Electronic Control System Description; Immobilizer Control System - Suzuki SX4 Service Manual

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1A-12 Engine General Information and Diagnosis:
Operation Description
ECM (5) detects opening (depressed extent of pedal) of the accelerator pedal based on signal voltage of the APP
sensor (1) and using that data and engine operation condition, it calculates the optimum throttle valve opening. On the
other hand, it detects the throttle valve opening based on the signal voltage of the throttle position sensor (3) included
in the throttle body (2) and compares it with the above calculated optimum throttle valve opening. When there is a
difference between them, ECM controls the duty ratio (100% – 0%) according to this difference to drive the throttle
actuator (motor) (4) included in the throttle body. When there is no difference, ECM controls the duty ratio to about
15% to maintain the throttle valve opening. In this way, the throttle valve (17) is opened and closed to achieve the
optimum throttle valve opening.
In this system, as the throttle position sensor and APP sensor have 2 sensors (main and sub) each, highly accurate
and highly reliable control and abnormality detection are assured. Also, when ECM detects an abnormality in the
system, it turns off the throttle actuator control relay (8) to stop controlling the throttle actuator. When the throttle
actuator control relay is turned off, the throttle valve is fixed at the opening of about 7° from its completely closed
position (default opening) by the force of the return spring and open spring included in the throttle body.
This throttle body is not equipped with IAC valve for idle speed control. Idle speed control is done by the throttle
actuator which opens/closes the throttle valve.
6. CPU
7. Drive circuit of throttle actuator
9. From "THR MOT" fuse
10. From main relay

Electronic Control System Description

The electronic control system consists of 1) various
sensors which detect the state of engine and driving
conditions, 2) ECM which controls various devices
according to the signals from the sensors and 3) various
controlled devices.
Functionally, it is divided into the following sub systems:
• Fuel injection control system
• Ignition control system
• Electric throttle body control system
• Fuel pump control system
• Radiator cooling fan control system
• Evaporative emission control system
• EGR system (if equipped)
11. APP sensor (main) signal
12. APP sensor (sub) signal
13. Throttle position sensor (main) signal
14. Throttle position sensor (sub) signal
15. Drive signal of throttle actuator
16. Power supply of throttle actuator
18. Control signal of throttle actuator control relay
• Oxygen sensor heater control system
• A/C control system (if equipped with A/C)
• Camshaft position control system

• Immobilizer control system

• Controller (computer) communication system
Especially, ECM (Engine Control Module), BCM (Body
electrical Control Module), combination meter, ABS /
ESP® control module, keyless start control module (if
equipped with keyless start control system), TCM
(Transmission Control Module) (for A/T model) and 4WD
control module (if equipped) intercommunicate by
means of CAN (Controller Area Network)
Refer to "Engine and Emission Control System Flow
Diagram" and "ECM Input / Output Circuit Diagram".


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