2001 INFINITI QX4 02 sensor

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
92 G/BFuel tank temperature
sensor[Engine is running]Approximately 0 - 4.8V
Output voltage varies with
fuel tank temperature.
93 W Knock sensor[Engine is running]
IIdle speedApproximately 2.5V
101
102
103
104
105
107R/B
L/W
R/W
PU/R
R/Y
R/LInjector No. 1
Injector No. 5
Injector No. 2
Injector No. 6
Injector No. 3
Injector No. 4[Engine is running]
IIdle speedBATTERY VOLTAGE
(11 - 14V)
106
108B
BECM ground[Engine is running]
IIdle speedEngine ground
11 0
11 2B/W
B/WPower supply for ECM[Ignition switch ªONº]BATTERY VOLTAGE
(11 - 14V)
111 P/B Sensors' power supply[Ignition switch ªONº]Approximately 5V
114 G/RCommunication line
(LAN)[Engine is running]
IIdle speedApproximately 2V
115 LG/R Data link connector[Ignition switch ªONº]
ICONSULT-II or GST is disconnected.Approximately 2V
H: Average voltage for pulse signal (Actual pulse signal can be confirmed by oscilloscope.)
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TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTION
ECM Terminals and Reference Value (Cont'd)
EC-135

DescriptionNBEC0717The specification (SP) value indicates the tolerance of the value that is displayed in ªDATA MONITOR (SPEC)º
mode of CONSULT-II during normal operation of the Engine Control System. When the value in ªDATA MONI-
TOR (SPEC)º mode is within the SP value, the Engine Control System is confirmed OK. When the value in
ªDATA MONITOR (SPEC)º mode is NOT within the SP value, the Engine Control System may have one or
more malfunctions.
The SP value is used to detect malfunctions that may affect the Engine Control System, but will not light the
MIL.
The SP value will be displayed for the following three items:
IB/FUEL SCHDL (The fuel injection pulse width programmed into ECM prior to any learned on board cor-
rection)
IA/F ALPHA-B1/B2 (The mean value of air-fuel ratio feedback correction factor per cycle)
IMAS A/F SE-B1 (The signal voltage of the mass air flow sensor)
Testing ConditionNBEC0718IVehicle driven distance: More than 5,000 km (3,100 miles)
IBarometric pressure: 101.3 kPa (760.0 mmHg, 29.92 inHg)±3 kPa (22.5 mmHg, 0.89 inHg)
IAtmospheric temperature: 20 - 30ÉC (68 - 86ÉF)
IEngine coolant temperature: 75 - 95ÉC (167 - 203ÉF)
ITransmission: Warmed-up*1
IElectrical load: Not applied*2
IEngine speed: Idle
*1: For A/T models, after the engine is warmed up to normal operating temperature, drive vehicle until ªFLUID
TEMP SEº (A/T fluid temperature sensor signal) indicates less than 0.9V.
*2: Rear window defogger switch, air conditioner switch, lighting switch are ªOFFº. Cooling fans are not oper-
ating. Steering wheel is straight ahead.
SEF601Z
Inspection ProcedureNBEC0719NOTE:
Perform ªDATA MONITOR (SPEC)º mode in maximum scale dis-
play.
1. Perform ªBasic Inspectionº, EC-101.
2. Confirm that the testing conditions indicated above are met.
3. Select ªB/FUEL SCHDLº, ªA/F ALPHA-B1º, ªA/F ALPHA-B2º
and ªMAS A/F SE-B1º in ªDATA MONITOR (SPEC)º mode with
CONSULT-II.
4. Make sure that monitor items are within the SP value.
5. If NG, go to ªDiagnostic Procedureº, EC-137.
TROUBLE DIAGNOSIS Ð SPECIFICATION VALUE
Description
EC-136

SEF958Y
Component DescriptionNBEC0050The mass air flow sensor is placed in the stream of intake air. It
measures the intake flow rate by measuring a part of the entire
intake flow. It consists of a hot film that is supplied with electric
current from the ECM. The temperature of the hot film is controlled
by the ECM a certain amount. The heat generated by the hot film
is reduced as the intake air flows around it. The more air, the
greater the heat loss.
Therefore, the ECM must supply more electric current to maintain
the temperature of the hot film as air flow increases. The ECM
detects the air flow by means of this current change.
CONSULT-II Reference Value in Data Monitor
Mode
NBEC0051Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
MAS A/F SE-B1IEngine: After warming up
IAir conditioner switch: ªOFFº
IShift lever: ªNº
INo-loadIdle 1.2 - 1.8V
2,500 rpm 1.6 - 2.2V
CAL/LD VALUE dittoIdle 14.0 - 33.0%
2,500 rpm 12.0 - 25.0%
MASS AIRFLOW dittoIdle 2.0 - 6.0 g´m/s
2,500 rpm 7.0 - 20.0 g´m/s
ECM Terminals and Reference ValueNBEC0649Specification 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)
61 OR Mass air flow sensor[Engine is running]
IWarm-up condition
IIdle speed1.2 - 1.8V
[Engine is running]
IWarm-up condition
IEngine speed is 2,500 rpm.1.6 - 2.2V
73 B/PMass air flow sensor
ground[Engine is running]
IWarm-up condition
IIdle speedApproximately 0V
111 P/B Sensors' power supply[Ignition switch ªONº]Approximately 5V
DTC P0100 MASS AIR FLOW SENSOR (MAFS)
Component Description
EC-150

On Board Diagnosis LogicNBEC0053Malfunction is detected when
(Malfunction A)an excessively high voltage from the sensor is
sent to ECM when engine is not running,
(Malfunction B)an excessively low voltage from the sensor is sent
to ECM when engine is running,
(Malfunction C)a high voltage from the sensor is sent to ECM
under light load driving condition,
(Malfunction D)a low voltage from the sensor is sent to ECM
under heavy load driving condition,
(Malfunction E)a voltage from the sensor is constantly approx.
1.0V when engine is running.
FAIL-SAFE MODENBEC0053S02When the malfunction B is detected, the ECM enters fail-safe mode
and the MIL lights up.
Detected items Engine operating condition in fail-safe mode
Mass air flow sensor circuit Engine speed will not rise more than 2,400 rpm due to the fuel cut.
Possible CauseNBEC0426MALFUNCTION A OR CNBEC0426S01IHarness or connectors
(The sensor circuit is open or shorted.)
IMass air flow sensor
MALFUNCTION B, D OR ENBEC0426S02IHarness or connectors
(The sensor circuit is open or shorted.)
IIntake air leaks
IMass air flow sensor
DTC Confirmation ProcedureNBEC0054Perform ªPROCEDURE FOR MALFUNCTION Aº first.
If the 1st trip DTC cannot be confirmed, perform ªPROCE-
DURE FOR MALFUNCTION B AND Eº.
If there is no problem on ªPROCEDURE FOR MALFUNCTION
B AND Eº, perform ªPROCEDURE FOR MALFUNCTION Cº.
If there is no problem on ªPROCEDURE FOR MALFUNCTION
Cº, perform ªPROCEDURE FOR MALFUNCTION Dº.
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.
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DTC P0100 MASS AIR FLOW SENSOR (MAFS)
On Board Diagnosis Logic
EC-151

SEF058Y
PROCEDURE FOR MALFUNCTION ANBEC0054S01With CONSULT-IINBEC0054S01011) Turn ignition switch ªONº.
2) Select ªDATA MONITORº mode with CONSULT-II.
3) Wait at least 6 seconds.
4) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-155.
With GSTNBEC0054S0102Follow the procedure ªWith CONSULT-IIº above.
SEF058Y
PROCEDURE FOR MALFUNCTION B AND ENBEC0054S02With CONSULT-IINBEC0054S02011) Turn ignition switch ªONº.
2) Select ªDATA MONITORº mode with CONSULT-II.
3) Start engine and wait 5 seconds at most.
4) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-155.
With GSTNBEC0054S0202Follow the procedure ªWith CONSULT-IIº above.
NOTE:
If 1st trip DTC is confirmed after more than 5 seconds, there may
be malfunction C.
SEF174Y
PROCEDURE FOR MALFUNCTION CNBEC0054S03NOTE:
If engine will not start or stops soon, wait at least 10 seconds with
engine stopped (Ignition switch ªONº) instead of running engine at
idle speed.
With CONSULT-IINBEC0054S03011) Turn ignition switch ªONº.
2) Select ªDATA MONITORº mode with CONSULT-II.
3) Start engine and warm it up to normal operating temperature.
4) Run engine for at least 10 seconds at idle speed.
5) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-155.
With GSTNBEC0054S0302Follow the procedure ªWith CONSULT-IIº above.
DTC P0100 MASS AIR FLOW SENSOR (MAFS)
DTC Confirmation Procedure (Cont'd)
EC-152

SEF243Y
SEF175Y
PROCEDURE FOR MALFUNCTION DNBEC0054S04CAUTION:
Always drive vehicle at a safe speed.
With CONSULT-IINBEC0054S04021) Turn ignition switch ªONº.
2) Start engine and warm it up to normal operating temperature.
If engine cannot be started, go to ªDiagnostic Procedureº,
EC-155.
3) Select ªDATA MONITORº mode with CONSULT-II.
4) Check the voltage of MAS AIR/FL SE with ªDATA MONITORº.
5) Increases engine speed to about 4,000 rpm.
6) Monitor the linear voltage rise in response to engine speed
increases.
If NG, go to ªDiagnostic Procedureº, EC-155.
If OK, go to following step.
7) Maintain the following conditions for at least 10 consecutive
seconds.
ENG SPEED More than 2,000 rpm
THRTL POS SEN More than 3V
Selector lever Suitable position
Driving location Driving vehicle uphill (Increased engine load)
will help maintain the driving conditions
required for this test.
8) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-155.
SEF534P
Overall Function CheckNBEC0055PROCEDURE FOR MALFUNCTION DNBEC0055S01Use this procedure to check the overall function of the mass air flow
sensor circuit. During this check, a 1st trip DTC might not be con-
firmed.
With GSTNBEC0055S01011) Start engine and warm it up to normal operating temperature.
2) Select ªMODE 1º with GST.
3) Check the mass air flow sensor signal with ªMODE 1º.
4) Check for linear mass air flow sensor signal value rise in
response to increases to about 4,000 rpm in engine speed.
5) If NG, go to ªDiagnostic Procedureº, EC-155.
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DTC P0100 MASS AIR FLOW SENSOR (MAFS)
DTC Confirmation Procedure (Cont'd)
EC-153

Wiring DiagramNBEC0056
MEC942C
DTC P0100 MASS AIR FLOW SENSOR (MAFS)
Wiring Diagram
EC-154

Diagnostic ProcedureNBEC0057
1 INSPECTION START
Which malfunction (A, B, C, D or E) is duplicated?
MTBL0373
Type I or Type II
Type I©GO TO 3.
Type II©GO TO 2.
2 CHECK INTAKE SYSTEM
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 3.
NG©Reconnect the parts.
3 RETIGHTEN GROUND SCREWS
1. Turn ignition switch ªOFFº.
2. Loosen and retighten engine ground screws.
SEF959Y
©GO TO 4.
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DTC P0100 MASS AIR FLOW SENSOR (MAFS)
Diagnostic Procedure
EC-155