2001 INFINITI QX4 engine coolant

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

Wiring DiagramNBEC0072
MEC945C
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DTC P0115 ENGINE COOLANT TEMPERATURE SENSOR (ECTS) (CIRCUIT)
Wiring Diagram
EC-171

Diagnostic ProcedureNBEC0073
1 CHECK ECTS POWER SUPPLY CIRCUIT
1. Turn ignition switch ªOFFº.
2. Disconnect engine coolant temperature sensor (ECTS) harness connector F112, F28.
SEF370Z
3. Turn ignition switch ªONº.
4. Check voltage between ECTS harness connector F28 terminal 3 and ground with CONSULT-II or tester.
SEF371Z
OK or NG
OK©GO TO 3.
NG©GO TO 2.
2 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors F112, F28
IHarness for open or short between ECM and engine coolant temperature sensor
©Repair harness or connectors.
3 CHECK ECTS GROUND CIRCUIT FOR OPEN AND CIRCUIT
1. Turn ignition switch ªOFFº.
2. Check harness continuity between ECTS terminal 2 and engine ground.
Refer to Wiring Diagram.
Continuity should exist.
3. Also check harness for short to power.
OK or NG
OK©GO TO 5.
NG©GO TO 4.
DTC P0115 ENGINE COOLANT TEMPERATURE SENSOR (ECTS) (CIRCUIT)
Diagnostic Procedure
EC-172

4 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors F112, F28
IHarness for open between ECM and engine coolant temperature sensor
IHarness for open between TCM (Transmission Control Module) and engine coolant temperature sensor
©Repair open circuit or short to power in harness or connectors.
5 CHECK ENGINE COOLANT TEMPERATURE SENSOR
Check resistance between engine coolant temperature sensor terminals 1 and 2 as shown in the figure.
SEF304X
OK or NG
OK©GO TO 6.
NG©Replace engine coolant temperature sensor.
6 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
©INSPECTION END
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DTC P0115 ENGINE COOLANT TEMPERATURE SENSOR (ECTS) (CIRCUIT)
Diagnostic Procedure (Cont'd)
EC-173

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