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Infiniti Q45 (FY33). Manual - part 155

SEF152P

COMPONENT INSPECTION

Engine coolant temperature sensor

Check resistance as shown in the figure.

SEF012P

Temperature °C (°F)

Resistance k

Ω

20 (68)

2.1 - 2.9

50 (122)

0.68 - 1.00

90 (194)

0.236 - 0.260

If NG, replace engine coolant temperature sensor.

IDX

TROUBLE DIAGNOSIS FOR DTC P0115

Engine Coolant Temperature Sensor (ECTS)
(Cont’d)

EC-149

Throttle Position Sensor

NOTE: If DTC P0510 (0203) is displayed with DTC P0120, perform TROUBLE DIAGNOSIS FOR DTC

P0510 first (See EC-346.).

COMPONENT DESCRIPTION

The throttle position sensor responds to the accelerator pedal movement. This sensor is a kind of potentiom-
eter which transforms the throttle position into output voltage, and emits the voltage signal to the ECM. In
addition, the sensor detects the opening and closing speed of the throttle valve and feeds the voltage signal
to the ECM.
Idle position of the throttle valve is determined by the ECM receiving the signal from the throttle position sen-
sor. This one controls engine operation such as fuel cut. The throttle position sensor unit has a built-in “Wide
open and closed throttle position switch”.

SEF121TA

CONSULT-II REFERENCE VALUE IN DATA MONITOR MODE

Specification data are reference values.

MONITOR ITEM

CONDITION

SPECIFICATION

THRTL POS SEN

Engine: After warming up

Ignition switch: ON
(Engine stopped)

More than −40.0 kPa (−300 mmHg,
−11.81 inHg) of vacuum is applied to
the throttle opener with a handy
vacuum pump.

Throttle valve: fully closed

0.15 - 0.85V

Throttle valve: fully opened

3.5 - 4.7V

ABSOL TH

⋅

P/S

Engine: After warming up

Ignition switch: ON
(Engine stopped)

More than −40.0 kPa (−300 mmHg,
−11.81 inHg) of vacuum is applied to
the throttle opener with a handy
vacuum pump.

Throttle valve fully closed

0.0%

Throttle valve fully opened

Approx. 88%

TROUBLE DIAGNOSIS FOR DTC P0120

EC-150

ECM TERMINALS AND REFERENCE VALUE

Specification data are reference values, and are measured between each terminal and ground.

CAUTION:

Do not use ECM ground terminals when measuring voltage. Doing so may result in damage to the
ECM’s transistor. Use a ground other than ECM terminals such as the body ground.

TER-

MINAL

NO.

WIRE

COLOR

ITEM

CONDITION

DATA

(DC voltage)

Throttle position sensor
signal

Ignition switch “ON” (Warmed-up condition)*

Accelerator pedal fully released

0.15 - 0.85V

Ignition switch “ON”

Accelerator pedal fully depressed

3.5 - 4.7V

BR/W

Sensor’s power supply

Ignition switch “ON”

Approximately 5V

129

Sensor’s ground

Engine is running. (Warmed-up condition)

Idle speed

*: More than −40.0 kPa (−300 mmHg, −11.81 inHg) of vacuum is applied to the throttle opener with a handy vacuum pump

ON BOARD DIAGNOSIS LOGIC

Diagnostic

Trouble

Code No.

Malfunction is detected when ...

Check Items

(Possible Cause)

P0120
0403

A) An excessively low or high voltage from the sensor is

sent to ECM.*

Harness or connectors
(The throttle position sensor circuit is open or shorted.)

Throttle position sensor

B) A high voltage from the sensor is sent to ECM under

light load driving condition.

Harness or connectors
(The throttle position sensor circuit is open or shorted.)

Throttle position sensor

Fuel injector

Camshaft position sensor

Mass air flow sensor

C) A low voltage from the sensor is sent to ECM under

heavy load driving condition.

Harness or connectors
(The throttle position sensor circuit is open or shorted.)

Intake air leaks

Throttle position sensor

*: When this malfunction is detected, the ECM enters fail-safe mode and the MIL lights up.

Engine operating condition in fail-safe mode

Condition

Driving condition

Throttle position will be determined based on the
amount of mass air flow and the engine speed.
Therefore, acceleration will be poor.

When engine is idling

Normal

When accelerating

Poor acceleration

Perform “Procedure for malfunction A” first. If the DTC cannot
be confirmed, perform “Procedure for malfunction B”. If there
is no problem on “Procedure for malfunction B”, perform
“Procedure for malfunction C”.

DIAGNOSTIC TROUBLE CODE CONFIRMATION
PROCEDURE

NOTE:
If “DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCE-
DURE” has been previously conducted, always turn ignition
switch “OFF” and wait at least 5 seconds before conducting
the next test.

IDX

TROUBLE DIAGNOSIS FOR DTC P0120

Throttle Position Sensor (Cont’d)

EC-151

SEF264Y

Procedure for malfunction A

CAUTION:

Always drive vehicle at a safe speed.
TESTING CONDITION:

Before performing the following procedure, confirm that
battery voltage is more than 10V at idle.

This test may be conducted with the drive wheels lifted in
the shop or by driving the vehicle. If a road test is
expected to be easier, it is unnecessary to lift the vehicle.

1) Turn ignition switch “ON” and select “DATA MONITOR”

mode with CONSULT-II.

2) Start engine and maintain the following conditions for at

least 5 consecutive seconds.
VHCL SPEED SE: More than 4 km/h (2 MPH)
Selector lever: Suitable position except “P” or “N”

position

3) If 1st trip DTC is detected, go to “DIAGNOSTIC

PROCEDURE”, EC-155.

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ OR ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Follow the procedure “With CONSULT-II” above.

SEF261Y

Procedure for malfunction B

1) Turn ignition switch “ON”.
2) Select “DATA MONITOR” mode with CONSULT-II.
3) Start engine and let it idle for at least 10 seconds. If idle

speed is over 1,100 rpm, maintain the following condi-
tions for at least 10 seconds to keep engine speed
below 1,100 rpm.
Selector lever: Suitable position except “P” or “N”
Brake pedal: depressed
Vehicle speed: 0 km/h (0 MPH)

4) If 1st trip DTC is detected, go to “DIAGNOSTIC

PROCEDURE”, EC-156.

Follow the procedure “With CONSULT-II” above.

SEF177Y

Procedure for malfunction C

1) Start engine and warm it up to normal operating tem-

perature.

2) Turn ignition switch “OFF” and wait at least 5 seconds.
3) Turn ignition switch “ON”.
4) Select “MANU TRIG” in “DATA MONITOR” mode with

CONSULT-II.

5) Select “THRTL POS SEN” and “ABSOL TH

⋅

P/S” in

“DATA MONITOR” mode with CONSULT-II.

TROUBLE DIAGNOSIS FOR DTC P0120

Throttle Position Sensor (Cont’d)

EC-152

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