Suzuki Grand Vitara JB416 / JB420. Manual - part 15

1A-9 Engine General Information and Diagnosis:

Air Intake System Description

S5JB0A1101006

The main components of the air intake system are air cleaner (1), air cleaner outlet hose (2), electric throttle body (3)
(for the details, refer to “Electric Throttle Body System Description”.), intake manifold tuning (IMT) valve (4) which
adjusts the distributor pipe length of intake manifold to (A) or (B) (for J20 engine) (for the details, refer to “IMT (Intake
Manifold Tuning) System Description: For J20 Engine in Section 1D”.) and intake manifold (5).
The air (by the amount corresponding to throttle valve (6) opening and engine speed) is filtered by the air cleaner,
distributed by the intake, and finally drawn into each combustion chamber.Electric throttle body is not equipped with
IAC valve for idle speed control. Idle speed control is done by the throttle actuator (7) which opens/closes the throttle
valve. (For the details, refer to “Electric Throttle Body System Description”)

[B]

[A]

I5JB0A110008-02

[A]: For J20 engine
[B]: For M16 engine

Engine General Information and Diagnosis: 1A-10

Electric Throttle Body System Description

S5JB0A1101009

The Electric Throttle Body System consists of electric throttle body assembly, accelerator pedal position (APP) sensor
assembly, ECM and throttle actuator control relay.
Among them, assembly components are as follows.
• Electric throttle body assembly: throttle valve, throttle actuator, 2 throttle position sensors
• Accelerator pedal position (APP) sensor assembly: Accelerator pedal, 2 accelerator position sensors

Operation Description
ECM (5) detects opening (depressed extent of pedal) of the accelerator pedal based on signal voltage of the
accelerator pedal position (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%) of throttle
actuator control 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 of throttle actuator control 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 accelerator pedal position (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.

I4RS0B110007-02

6. CPU

11.

Accelerator pedal position (APP) sensor
(main) signal

15. Drive signal of throttle actuator

7. Drive circuit of throttle actuator

12.

Accelerator pedal position (APP) sensor (sub)
signal

16. Power supply of throttle actuator

9. From “THR MOT” fuse

13.

Throttle position sensor (main) signal

18. Control signal of throttle actuator control relay

10. From main relay

14.

Throttle position sensor (sub) signal

1A-11 Engine General Information and Diagnosis:

Description of Electric Throttle Body System Calibration

S5JB0A1101010

ECM calculates controlled opening of the throttle valve on the basis of the completely closed throttle valve position of
the electric throttle body system. The completely closed position data is saved in memory of ECM. However, the
completely closed position of the throttle valve of the electric throttle body system (signal voltage from throttle position
sensor when throttle is completely closed) differs one from the other depending on individual differences of the throttle
valve and throttle position sensor. As such individual differences must be taken into account for controlling the throttle
valve, it is necessary to register the completely closed throttle valve position data in ECM. When such data is
registered in ECM, it is saved in RAM (memory) of ECM and used as the base data for controlling the throttle valve.
This data is cleared, when any of the works described in “Precautions of Electric Throttle Body System Calibration” is
performed.
Also, after replacement of the throttle body and/or accelerator pedal position (APP) sensor assembly, the completely
closed position data in memory of ECM must be cleared once and a new one must be registered, or ECM cannot
judge the complete closure position properly.
For the procedure to register such data, refer to “Electric Throttle Body System Calibration in Section 1C”. (After the
completely closed position data is cleared, ECM, for the first time only, opens and closes the throttle valve for about 5
seconds after the ignition switch is turned ON position, for registration of the completely closed throttle valve position.
If the engine is started during this registration process, such symptom as “longer cranking time” or “slow rise of
revolution speed immediately after start-up” may occur. However, turning OFF the ignition switch once and restarting
will set correct registration.)

Generator Control System Description

S5JB0A1101011

Generator Control System consists of a generator (1), electric load current sensor (7) (for J20 engine) located in the
fuse box No.1 (4) and ECM (5).
ECM controls generated electricity (adjusting voltage of IC regulator (2)) so that it is suitable for the engine and electric
load conditions. When the electric load increases quickly, generation load of the generator increases quickly and
causes idling to change. To prevent this, ECM makes generated electricity volume vary gradually to stabilize idling.
Also, it reduces the engine load caused by temporary increase in electricity generation to cope with the engine
condition (such as when accelerating).

Operation
ECM controls the generated voltage of the generator using “C” terminal (generator control terminal) duty, based on
following information.
• Engine condition (ECT, vehicle speed, engine speed, TP, etc.) (9)
• Battery voltage (ECM backup power voltage) (10)
• Electric load condition (blower motor, rear defogger, head lights, radiator fan, A/C, etc.) (11)
• “FR” terminal output (field coil (3) control duty) which indicates the operation rate (electricity generation condition) of

the generator.

Engine General Information and Diagnosis: 1A-12

Then the generator uses “C” terminal duty to regulate the adjusting voltage of the IC regulator with the field coil control
duty so as to control its generated voltage (“B” terminal output voltage).
(For more information of the generated voltage, refer to Charging System in Section 1J.)
Furthermore, with the J20 engine, the generation condition of the generator is controlled to the optimum level by the
electric load current sensor (7) which detects the electrical load condition (current consumption) linearly even when a
sudden electrical load variation occurs and thus the engine load is reduced.

A/F Sensor Description

S5JB0A1101012

A/F sensor (1), in place of the conventional heated Oxygen sensor-1, is installed in the center of the exhaust manifold
joining section and it consists of a zirconia element (2) which causes the output current to vary according to difference
in the oxygen concentration, a heater (3) which activates the element and an adjusting resistor (4) which adjusts
individual difference of the sensor.
A/F sensor detects oxygen concentration in exhaust gas (9) (A/F ratio of the air-fuel mixture) linearly, ranging from
LEAN to RICH.

Operation
ECM (5) controls the sensor heater (3) and keeps the sensor element temperature at the specified level (about 750

°C) constantly so that the A/F sensor is activated in the specified way for accurate A/F detection. When the sensor
element reaches the specified temperature (it is activated), its impedance drops to the specified value (approx. 30

Ω)

by its characteristic.
When a certain voltage (about 0.4 V) is applied between sensor elements in this state, circuit current corresponding to
the sensor element impedance flows in the sensor circuit. ECM detects this circuit current and judges whether the
sensor is in the active state or not. At this time, sensor current is output linearly in the range of +0.01 mA to +some mA
on the lean side and –0.01 mA to – some mA on the rich side. The variation in these ranges depends on the difference
from the stoichiometry A/F ratio, that is, the amount of oxygen between the atmosphere side (6) and exhaust manifold
(7).
According to this sensor output, ECM executes A/F feedback (fuel trim) to achieve the target A/F ratio.

The A/F sensor connector (8) is provided with an adjusting resistor (4) ECM detects the adjusting resistance value and
corrects the sensor output current value.

CMO
CMG

CMV

FCD

GCD

I5JB0A110009-01

6. Ignition switch

8. Battery

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