2001 INFINITI QX4 elec

DescriptionNBEC0045Intermittent incidents (I/I) may occur. In many cases, the problem resolves itself (the part or circuit function
returns to normal without intervention). It is important to realize that the symptoms described in the custom-
er's complaint often do not recur on (1st trip) DTC visits. Realize also that the most frequent cause of I/I
occurrences is poor electrical connections. Because of this, the conditions under which the incident occurred
may not be clear. Therefore, circuit checks made as part of the standard diagnostic procedure may not indi-
cate the specific problem area.
COMMON I/I REPORT SITUATIONSNBEC0045S01
STEP in Work Flow Situation
II The CONSULT-II is used. The SELF-DIAG RESULTS screen shows time data other than ª0º or ª[1t]º.
III The symptom described by the customer does not recur.
IV (1st trip) DTC does not appear during the DTC Confirmation Procedure.
VI The Diagnostic Procedure for PXXXX does not indicate the problem area.
Diagnostic ProcedureNBEC0046
1 INSPECTION START
Erase (1st trip) DTCs. Refer to ªHOW TO ERASE EMISSION Ð RELATED INFORMATIONº, EC-72.
©GO TO 2.
2 CHECK GROUND TERMINALS
Check ground terminals for corroding or loose connection.
Refer to GI-30, ªGROUND INSPECTIONº.
OK or NG
OK©GO TO 3.
NG©Repair or replace.
3 SEARCH FOR ELECTRICAL INCIDENT
Perform GI-36, ªIncident Simulation Testsº.
OK or NG
OK©GO TO 4.
NG©Repair or replace.
4 CHECK CONNECTOR TERMINALS
Refer to GI-27, ªHow to Check Enlarged Contact Spring of Terminalº.
OK or NG
OK©INSPECTION END
NG©Repair or replace connector.
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT
Description
EC-140

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

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.
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0100 MASS AIR FLOW SENSOR (MAFS)
DTC Confirmation Procedure (Cont'd)
EC-153

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.
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
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.
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
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)
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0115 ENGINE COOLANT TEMPERATURE SENSOR (ECTS) (CIRCUIT)
Component Description
EC-169