elec INFINITI QX4 2001 Factory Service Manual

Possible CauseNBEC0728IHarness or connectors
(Absolute pressure sensor circuit is open or shorted.)
IAbsolute pressure sensor
DTC Confirmation ProcedureNBEC0729NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 10 seconds
before conducting the next test.
SEF058Y
WITH CONSULT-IINBEC0729S011) Turn ignition switch ªONº.
2) Select ªDATA MONITORº mode with CONSULT-II.
3) Wait at least 10 seconds.
4) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-161.
WITH GSTNBEC0729S02Follow the procedure ªWITH CONSULT-IIº above.
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DTC P0105 ABSOLUTE PRESSURE SENSOR
Possible Cause
EC-159

SEF962Y
SEF012P
Component DescriptionNBEC0064The intake air temperature sensor is mounted to the air duct hous-
ing. The sensor detects intake air temperature and transmits a sig-
nal to the ECM.
The temperature sensing unit uses a thermistor which is sensitive
to the change in temperature. Electrical resistance of the thermistor
decreases in response to the temperature rise.

Intake air
temperature ÉC (ÉF)Voltage* V Resistance kW
20 (68) 3.5 2.1 - 2.9
80 (176) 1.23 0.27 - 0.38
*: These data are reference values and are measured between ECM terminal 64
(Intake air temperature sensor) and body ground.
CAUTION:
Do not use ECM ground terminals when measuring input/
output voltage. Doing so may result in damage to the ECM's
transistor. Use a ground other than ECM terminals, such as
the ground.
On Board Diagnosis LogicNBEC0065Malfunction is detected when
(Malfunction A)an excessively low or high voltage from the sen-
sor is sent to ECM,
(Malfunction B)rationally incorrect voltage from the sensor is sent
to ECM, compared with the voltage signal from engine coolant
temperature sensor.
Possible CauseNBEC0428IHarness or connectors
(The sensor circuit is open or shorted.)
IIntake air temperature sensor
DTC Confirmation ProcedureNBEC0066Perform ªPROCEDURE FOR MALFUNCTION Aº first. If 1st trip
DTC cannot be confirmed, perform ªPROCEDURE FOR MAL-
FUNCTION Bº.
NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 10 seconds
before conducting the next test.
DTC P0110 INTAKE AIR TEMPERATURE SENSOR
Component Description
EC-164

SEF058Y
PROCEDURE FOR MALFUNCTION ANBEC0066S01With CONSULT-IINBEC0066S01011) Turn ignition switch ªONº.
2) Select ªDATA MONITORº mode with CONSULT-II.
3) Wait at least 5 seconds.
4) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-167.
With GSTNBEC0066S0102Follow the procedure ªWith CONSULT-IIº above.
SEF176Y
PROCEDURE FOR MALFUNCTION BNBEC0066S02CAUTION:
Always drive vehicle at a safe speed.
TESTING CONDITION:
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.
With CONSULT-IINBEC0066S02011) Wait until engine coolant temperature is less than 90ÉC
(194ÉF).
a) Turn ignition switch ªONº.
b) Select ªDATA MONITORº mode with CONSULT-II.
c) Check the engine coolant temperature.
d) If the engine coolant temperature is not less than 90ÉC
(194ÉF), turn ignition switch ªOFFº and cool down engine.
IPerform the following steps before engine coolant temperature
is above 90ÉC (194ÉF).
2) Turn ignition switch ªONº.
3) Select ªDATA MONITORº mode with CONSULT-II.
4) Start engine.
5) Hold vehicle speed at more than 70 km/h (43 MPH) for 100
consecutive seconds.
6) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-167.
With GSTNBEC0066S0202Follow the procedure ªWith CONSULT-IIº above.
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DTC P0110 INTAKE AIR TEMPERATURE SENSOR
DTC Confirmation Procedure (Cont'd)
EC-165

SEF594K
Component DescriptionNBEC0069The engine coolant temperature sensor is used to detect the
engine coolant temperature. The sensor modifies a voltage signal
from the ECM. The modified signal returns to the ECM as the
engine coolant temperature input. The sensor uses a thermistor
which is sensitive to the change in temperature. The electrical
resistance of the thermistor decreases as temperature increases.
SEF012P

Engine coolant
temperature ÉC (ÉF)Voltage* V Resistance kW
þ10 (14) 4.4 7.0 - 11.4
20 (68) 3.5 2.1 - 2.9
50 (122) 2.2 0.68 - 1.00
90 (194) 0.9 0.236 - 0.260
*: These data are reference values and are measured between ECM terminal 70
(Engine coolant temperature sensor) and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/
output voltage. Doing so may result in damage to the ECM's
transistor. Use a ground other than ECM terminals, such as
the ground.
On Board Diagnosis LogicNBEC0070Malfunction is detected when an excessively high or low voltage
from the sensor is sent to ECM.
FAIL-SAFE MODENBEC0070S02When this malfunction is detected, the ECM enters fail-safe mode
and the MIL lights up.
Detected items Engine operating condition in fail-safe mode
Engine coolant tem-
perature sensor circuitEngine coolant temperature will be determined by ECM based on the time after turning ignition switch
ªONº or ªSTARTº.
CONSULT-II displays the engine coolant temperature decided by ECM.
ConditionEngine coolant temperature decided (CONSULT-II
display)
Just as ignition switch is turned ON or Start 40ÉC (104ÉF)
More than approx. 4 minutes after ignition ON or
Start80ÉC (176ÉF)
Except as shown above40 - 80ÉC (104 - 176ÉF)
(Depends on the time)
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DTC P0115 ENGINE COOLANT TEMPERATURE SENSOR (ECTS) (CIRCUIT)
Component Description
EC-169

Possible CauseNBEC0429IHarness or connectors
(The sensor circuit is open or shorted.)
IEngine coolant temperature sensor
SEF058Y
DTC Confirmation ProcedureNBEC0071NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 10 seconds
before conducting the next test.
WITH CONSULT-IINBEC0071S011) Turn ignition switch ªONº.
2) Select ªDATA MONITORº mode with CONSULT-II.
3) Wait at least 5 seconds.
4) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-172.
WITH GSTNBEC0071S02Follow the procedure ªWITH CONSULT-IIº above.
DTC P0115 ENGINE COOLANT TEMPERATURE SENSOR (ECTS) (CIRCUIT)
Possible Cause
EC-170

ICrankshaft position sensor (REF)
ICrankshaft position sensor (POS)
IMass air flow sensor
MALFUNCTION CNBEC0430S03IHarness or connectors
(The throttle position sensor circuit is open or shorted.)
IIntake air leaks
IThrottle position sensor
DTC Confirmation ProcedureNBEC0078NOTE:
IPerform ªPROCEDURE FOR MALFUNCTION Aº first. If the
1st trip DTC cannot be confirmed, perform ªPROCEDURE
FOR MALFUNCTION Bº.
If there is no problem on ªPROCEDURE FOR MALFUNC-
TION Bº, perform ªPROCEDURE FOR MALFUNCTION Cº.
IIf ªDTC Confirmation Procedureº has been previously
conducted, always turn ignition switch ªOFFº and wait at least
10 seconds before conducting the next test.
PROCEDURE FOR MALFUNCTION ANBEC0078S01CAUTION:
Always drive vehicle at a safe speed.
TESTING CONDITION:
IBefore performing the following procedure, confirm that
battery voltage is more than 10V at idle.
IThis 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.
SEF065Y
With CONSULT-IINBEC0078S01011) Turn ignition switch ªONº and select ªDATA MONITORº mode
with CONSULT-II.
2) Start engine and maintain the following conditions for at least
5 consecutive seconds.
Vehicle speed More than 5 km/h (3 MPH)
Selector lever Suitable position except ªPº or ªNº position
3) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-181.
With GSTNBEC0078S0102Follow the procedure ªWith CONSULT-IIº above.
DTC P0120 THROTTLE POSITION SENSOR
Possible Cause (Cont'd)
EC-176

SEF058Y
PROCEDURE FOR MALFUNCTION BNBEC0078S02With CONSULT-IINBEC0078S02011) Turn ignition switch ªONº.
2) Select ªDATA MONITORº mode with CONSULT-II.
3) Start engine and let it idle for at least 10 seconds.
If idle speed is over 1,000 rpm, maintain the following condi-
tions for at least 10 seconds to keep engine speed below 1,000
rpm.
Selector lever Suitable position except ªPº or ªNº
Brake pedal Depressed
Vehicle speed 0 km/h (0 MPH)
4) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-181.
With GSTNBEC0078S0202Follow the procedure ªWith CONSULT-IIº above.
SEF177Y
PROCEDURE FOR MALFUNCTION CNBEC0078S03CAUTION:
Always drive vehicle at a safe speed.
With CONSULT-IINBEC0078S03011) Start engine and warm it up to normal operating temperature.
2) Turn ignition switch ªOFFº and wait at least 10 seconds.
3) Turn ignition switch ªONº.
4) Select ªMANU TRIGº in ªDATA MONITORº mode with CON-
SULT-II.
5) Select ªTHRTL POS SENº and ªABSOL TH´P/Sº in ªDATA
MONITORº mode with CONSULT-II.
6) Press RECORD on CONSULT-II SCREEN at the same time
accelerator pedal is depressed.
7) Print out the recorded graph and check the following:
IThe voltage rise is linear in response to accelerator pedal
depression.
IThe voltage when accelerator pedal is fully depressed is
approximately 4V.
If NG, go to ªDiagnostic Procedureº, EC-181.
If OK, go to following step.
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DTC P0120 THROTTLE POSITION SENSOR
DTC Confirmation Procedure (Cont'd)
EC-177

SEF174Z
8) Select ªAUTO TRIGº in ªDATA MONITORº mode with CON-
SULT-II.
SEF178Y
9) Maintain the following conditions for at least 10 consecutive
seconds.
ENG SPEED More than 2,000 rpm
MAS A/F SE-B1 More than 3.2V
COOLAN TEMP/S More than 70ÉC (158ÉF)
Selector lever Suitable position
Driving location Driving vehicle uphill (Increased engine load)
will help maintain the driving conditions
required for this test.
10) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-181.
DTC P0120 THROTTLE POSITION SENSOR
DTC Confirmation Procedure (Cont'd)
EC-178

SEF305X
With GST=NBEC0078S03021) Start engine and warm it up to normal operating temperature.
2) Maintain the following conditions for at least 10 consecutive
seconds.
Gear position Suitable position
Engine speed More than 2,000 rpm
Engine coolant temperature More than 70ÉC (158ÉF)
Voltage between ECM termi-
nal 91 (Mass air flow sensor
signal) and groundMore than 3.2V
3) Select ªMODE 7º with GST.
4) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-181.
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DTC P0120 THROTTLE POSITION SENSOR
DTC Confirmation Procedure (Cont'd)
EC-179

8 CHECK THROTTLE POSITION SENSOR INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Disconnect ECM harness connector.
2. Check harness continuity between ECM terminal 91 and throttle position sensor terminal 2.
Refer to Wiring Diagram.
Continuity should exist.
3. Also check harness for short to ground and short to power.
OK or NG
OK (With CONSULT-II)©GO TO 9.
OK (Without CONSULT-
II)©GO TO 10.
NG©Repair open circuit or short to ground or short to power in harness or connectors.
9 CHECK THROTTLE POSITION SENSOR
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Stop engine (ignition switch OFF).
3. Remove the vacuum hose connected to the throttle opener.
4. Connect suitable vacuum hose to the vacuum pump and the opener.
5. Apply vacuum [more than ±40.0kPa (±300mmHg, ±11.81inHg)] until the throttle drum becomes free from the rod of the
throttle opener.
SEF793W
6. Turn ignition switch ON.
7. Select ªDATA MONITORº mode with CONSULT-II.
8. Check voltage of ªTHRTL POS SENº under the following conditions.
Voltage measurement must be made with throttle position sensor installed in vehicle.
SEF062Y
OK or NG
OK©GO TO 12.
NG©GO TO 11.
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DTC P0120 THROTTLE POSITION SENSOR
Diagnostic Procedure (Cont'd)
EC-183