IDX INFINITI QX4 2001 Factory Service Manual

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

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

ECM Terminals and Reference Value=NBEC0651Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
TERMI-
NAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
91 R Throttle position sensor[Engine is running]
IWarm-up condition
IAccelerator pedal fully released0.15 - 0.85V
[Ignition switch ªONº]
IAccelerator pedal fully depressed3.5 - 4.7V
111 P/B Sensors' power supply[Ignition switch ªONº]Approximately 5V
58 B/P Sensors' ground[Engine is running]
IWarm-up condition
IIdle speedApproximately 0V
On Board Diagnosis LogicNBEC0077Malfunction is detected when
(Malfunction A)an excessively low or high voltage from the sen-
sor is sent to ECM,
(Malfunction B)a high voltage from the sensor is sent to ECM
under light load driving conditions,
(Malfunction C)a low voltage from the sensor is sent to ECM
under heavy load driving conditions.
FAIL-SAFE MODENBEC0077S02When the malfunction A is detected, the ECM enters fail-safe mode
and the MIL lights up.
Detected items Engine operating condition in fail-safe mode
Throttle position sensor
circuitThrottle position will be determined based on the injected fuel amount and the engine speed.
Therefore, acceleration will be poor.
Condition Driving condition
When engine is idling Normal
When accelerating Poor acceleration
Possible CauseNBEC0430MALFUNCTION ANBEC0430S01IHarness or connectors
(The throttle position sensor circuit is open or shorted.)
IThrottle position sensor
MALFUNCTION BNBEC0430S02IHarness or connectors
(The throttle position sensor circuit is open or shorted.)
IThrottle position sensor
IFuel injector
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DTC P0120 THROTTLE POSITION SENSOR
ECM Terminals and Reference Value
EC-175

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

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

Diagnostic ProcedureNBEC0080
1 INSPECTION START
Which malfunction A, B or C is duplicated?
MTBL0066
TypeA,BorC
TypeAor B©GO TO 4.
Type C©GO TO 2.
2 ADJUST THROTTLE POSITION SENSOR
Check the following items. Refer to ªBasic Inspectionº, EC-101.
MTBL0655
©GO TO 3.
3 CHECK INTAKE SYSTEM.
1. Turn ignition switch ªOFFº.
2. Check the following for connection.
IAir duct
IVacuum hoses
IIntake air passage between air duct to intake manifold collector
OK or NG
OK©GO TO 4.
NG©Reconnect the parts.
4 RETIGHTEN GROUND SCREWS
1. Turn ignition switch ªOFFº.
2. Loosen and retighten engine ground screws.
SEF959Y
©GO TO 5.
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DTC P0120 THROTTLE POSITION SENSOR
Diagnostic Procedure
EC-181

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

12 CHECK MASS AIR FLOW SENSOR
1. Reconnect harness connectors disconneted.
2. Start engine and warm it up to normal operating temperature.
3. Check voltage between ECM terminal 61 (Mass air flow sensor signal) and ground.
SEF298X
4. If the voltage is out of specification, disconnect mass air flow sensor harness connector and connect it again.
Then repeat above check.
OK or NG
OK©GO TO 13.
NG©Replace mass air flow sensor.
13 CHECK CRANKSHAFT POSITION SENSOR (POS)
1. Install all removed parts.
2. Perform ªDTC Confirmation Procedureº for DTC P0335 and P1336. Refer to EC-336, 519.
OK or NG
OK©GO TO 14.
NG©Replace crankshaft position sensor (POS).
14 CHECK CRANKSHAFT POSITION SENSOR (REF)
Perform ªDTC Confirmation Procedureº for DTC P1335. Refer to EC-511.
OK or NG
OK©GO TO 15.
NG©Replace crankshaft position sensor (REF).
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DTC P0120 THROTTLE POSITION SENSOR
Diagnostic Procedure (Cont'd)
EC-185

DescriptionNBEC0081NOTE:
If DTC P0125 is displayed with P0115, first perform the trouble
diagnosis for DTC P0115. Refer to EC-169.
SEF594K
COMPONENT DESCRIPTIONNBEC0081S01The 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 9.2
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 LogicNBEC0082Malfunction is detected when voltage sent to ECM from the sen-
sor is not practical, even when some time has passed after start-
ing the engine, or engine coolant temperature is insufficient for
closed loop fuel control.
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DTC P0125 ENGINE COOLANT TEMPERATURE SENSOR (ECTS)
Description
EC-187

Wiring DiagramNBEC0084
MEC945C
GI
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PD
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BT
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DTC P0125 ENGINE COOLANT TEMPERATURE SENSOR (ECTS)
Wiring Diagram
EC-189