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Suzuki Grand Vitara JB627. Service manual - part 76

1C-2 Engine Electrical Devices:

Mass Air Flow (MAF) and Intake Air
Temperature (IAT) Sensor On-Vehicle
Inspection

S6JB0B1306002

MAF Sensor Signal Inspection

NOTE
Before performing this inspection, be sure to
read the “Precautions of ECM Circuit
Inspection in Section 1A”.

1) Remove ECM cover from bracket.
2) With ignition switch OFF, disconnect MAF and IAT

sensor connector (1).

3) Connect voltmeter between C13-2 terminal (2) and

C13-3 terminal (3) of MAF and IAT sensor connector
(1) disconnected.

4) Turn ignition switch ON and check that sensor power

supply is battery voltage. If not, check if wire harness
is open or connection is poor.

5) Turn ignition switch OFF and connect connector to

MAF and IAT sensor.

6) Check MAF sensor output voltage referring to

“Inspection of ECM and Its Circuits in Section 1A”.
If MAF sensor output voltage is not as specified,
cause may lie in wire harness, coupler connection,
MAF and IAT sensor or ECM.

Intake Air Temperature (IAT) Sensor Inspection

CAUTION

Do not heat up MAF and IAT sensor more
than 100

°C (212 °F). Otherwise, MAF and IAT

sensor will be damaged.

• Check sensor O-ring for damage and deterioration.

Replace as necessary.

• Blow hot air to temperature sensing part (1) of MAF

and IAT sensor (2) using hot air drier (3) and measure
resistance between IAT sensor terminals (5) and (6)
while heating air gradually.
If measured resistance does not show such
characteristic as shown, replace MAF and IAT sensor.

Intake air temperature sensor resistance
–20

°C (–4 °F): 12.5 – 16.9 kΩ

°C (77 °F): 1.8 – 2.2 kΩ

°C (140 °F): 0.5 – 0.68 kΩ

I6JB01130004-03

[A]: Lower limit
[B]: Nominal

[C]: Upper limit
[D]: Resistance

[E]: Temperature

4. Temperature gauge

104

140

176

(2.00)

(0.59)

[A]

[B]

[E]

[C]

[D]

I6JB01130005-03

Engine Electrical Devices: 1C-3

Mass Air Flow (MAF) and Intake Air
Temperature (IAT) Sensor Removal and
Installation

S6JB0B1306003

CAUTION

• Do not disassemble MAF and IAT sensor.
• Do not expose MAF and IAT sensor to any

shock.

• Do not clean MAF and IAT sensor.
• If MAF and IAT sensor has been dropped, it

should be replaced.

• Do not blow compressed air by using air

gun or the like.

• Do not put finger or any other object into

MAF and IAT sensor. Malfunction may
occur.

Removal

1) Disconnect negative cable at battery.
2) Disconnect MAF and IAT sensor connector.
3) Remove MAF and IAT sensor (1) from air cleaner

case.

Installation
Reverse removal procedure noting the followings.
• Tighten MAF and IAT sensor screws to specified

torque.

Tightening torque
MAF and IAT Sensor screw (a): 1.5 N·m (0.15 kgf-
m, 1.1 lb-ft)

• Connect MAF and IAT sensor connector securely.

Electric Throttle Body Assembly On-Vehicle
Inspection

S6JB0B1306004

WARNING

Never touch throttle valve with finger while
ignition switch is turned ON and accelerator
pedal is depressed. Otherwise, injury may
result by pinching the finger between throttle
valve and throttle body housing.

CAUTION

• Do not disassemble electric throttle body

assembly.

• Do not expose electric throttle body

assembly to excessive shock like a
dropping it. If electric throttle body
assembly has been exposed to excessive
shock, it should be replaced.

• Be careful not to accrete a foreign material

(like dust and/or metallic particle) to the
throttle body housing and/or throttle valve.
Otherwise, the throttle body assembly is
breaking down by throttle valve accretion.

• Do not apply excessive moving force to

throttle valve for throttle valve operation
check and/or TP sensor performance
check.
Otherwise, the throttle body assembly is
breaking down by damaging the internal
resinous gear of throttle valve actuator.

NOTE
After replacing electric throttle body
assembly, perform calibration of electric
throttle body assembly referring to “Electric
Throttle Body System Calibration”.

Throttle Valve Visual Check

1) Remove air intake pipe.
2) Check that there isn’t any foreign matter caught

between throttle valve and throttle body housing. If
there is, take it out after removing throttle body
referring to “Electric Throttle Body Assembly
Removal and Installation in Section 1D” and clean
inside of throttle body thoroughly.

I6JB01130006-01

(a)

I6JB01130007-01

1C-4 Engine Electrical Devices:

Throttle Valve Operation Check

1) Remove air intake pipe.
2) Turn OFF ignition switch and then disconnect

connector from electric throttle body assembly.

3) Move throttle valve with finger to its full open position

and check that it moves smoothly.

4) Move throttle valve with finger to its completely

closed position and check that it moves smoothly.

5) Take off finger from throttle valve (1) which is at full

open position and check that it moves smoothly by
its return spring and open spring force back to
default position (position where throttle valve is open
by 10

° (2) from completely closed position).

6) Take off finger from throttle valve (1) which is at

completely closed position and check that it moves
smoothly by its return spring and open spring force
back to default position.

If check result is not satisfactory, replace electric
throttle body assembly.

Electric Throttle Body Assembly Operation Check

1) Remove air intake pipe.
2) Turn ON ignition switch.
3) Depress accelerator pedal gradually and check that

throttle valve moves smoothly until it opens fully (1).

4) Release accelerator pedal depressed in Step 3) and

check that throttle valve (2) moves back to
completely closed position.

If check result is satisfactory, electric throttle body
system is in good condition. If check result is not
satisfactory, proceed to next step.

5) Perform “Accelerator Pedal Position (APP) Sensor

Assembly On-Vehicle Inspection”, “Throttle Actuator
(Motor) Check” and “Throttle Position Sensor
Performance Check”.
If check results are not satisfactory, replace electric
throttle body assembly.
If check results are satisfactory, wire circuit and/or
ECM are faulty.

Throttle Actuator (Motor) Check

1) Turn OFF ignition switch.
2) Disconnect connector from electric throttle body

assembly.

3) Measure resistance between “M1” terminal (1) and

“M2” terminal (2) of electric throttle body assembly.
If measured resistance is out of specified value,
replace electric throttle body assembly.

Throttle actuator (motor) resistance
0.3 – 100

Ω at 20 °C, 68 °F

I6JB01130008-01

I5JB0A130035-01

I6JB01130009-02

I6JB01130010-01

Engine Electrical Devices: 1C-5

Throttle Position Sensor Performance Check

1) Remove air intake pipe.
2) Turn OFF ignition switch.
3) Disconnect connector from electric throttle body

assembly.

4) Check throttle position sensor (main and sub) output

voltage as following steps.
a) For throttle position sensor (main), arrange 3

new 1.5 V batteries (1) in series (check that total
voltage is 4.7 – 5.0 V) and connect its positive
terminal to “Vin” terminal (2) and negative
terminal to “Ground” terminal (3) of sensor. Then
using voltmeter, connect positive terminal to
“Vout 1” terminal (4) of sensor and negative
terminal to battery.

b) For throttle position sensor (sub), arrange 3 new

1.5 V batteries (1) in series (check that total
voltage is 4.7 – 5.0 V) and connect its positive
terminal to “Vin” terminal (2) and negative
terminal to “Ground” terminal (3) of sensor. Then
using voltmeter, connect positive terminal to
“Vout 2” terminal (4) of sensor and negative
terminal to battery.

c) Measure output voltage variation while throttle

valve is opened and closed as following
specification.

If sensor voltage is out of specified value and linear
variation as the following graph, replace electric throttle
body assembly.

Throttle position sensor output voltage
Throttle position sensor (main) variation [A]: 0.304 –
4.325 V at minimum variation, varying according to
throttle valve opening by finger (Voltage should vary
by about 0.04 V for each 1

° valve opening)

Throttle position sensor (sub) variation [B]: 4.585 –
0.517 V at minimum variation, varying according to
throttle valve opening by finger (Voltage should vary
by about 0.04 V for each 1

° valve opening)

Electric Throttle Body System Calibration

S6JB0B1306005

NOTE
If working the service described under the
“Precautions of Electric Throttle Body
System Calibration in Section 1A”, perform
following steps for electric throttle body
system calibration.

1) If electric throttle body assembly and/or accelerator

pedal position (APP) sensor assembly are replaced,
perform following steps.
a) Disconnect negative cable at battery for 20

seconds or more for the purpose of clearing
calibration data of closed throttle position from
memory in ECM.

b) Connect negative cable to battery.

2) Keep ignition switch at ON position for 5 seconds or

more without running engine.

I6JB01130011-01

I6JB01130012-02

[C]: Throttle valve is completely closed position
[D]: Throttle valve is fully open position

[E]: Position where throttle valve is open by 10

° from completely closed

position (default position)

[F]: Angle obtained when accelerator pedal is depressed fully (84

°)

[B]

[A]

(V)

[E]

[C]

[D]

0.304 - 0.662

0.517- 0.945

3.317 - 4.247

0.587 - 1.213

3.558 - 4.325

3.793 - 4.585

[F]

[E]

[F]

I6JB01130013-01

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