2001 INFINITI QX4 Ac system

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

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.
GI
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PD
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DTC P0100 MASS AIR FLOW SENSOR (MAFS)
Diagnostic Procedure
EC-155

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.
GI
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LC
FE
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PD
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SU
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ST
RS
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IDX
DTC P0120 THROTTLE POSITION SENSOR
Diagnostic Procedure
EC-181

4 CHECK HEATED OXYGEN SENSOR 1 (FRONT)
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Set voltmeter probes between ECM terminal 63 (HO2S1 bank 1 right signal) or 62 (HO2S1 bank 2 left signal) and
engine ground.
3. Check the following with engine speed held at 2,000 rpm constant under no load.
SEF967XA
CAUTION:
Discard any heated oxygen sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a
hard surface such as a concrete floor; use a new one.
OK or NG
OK©GO TO 6.
NG©GO TO 5.
5 REPLACE HEATED OXYGEN SENSOR 1 (FRONT)
1. Turn ignition switch ªOFFº.
2. Check heated oxygen sensor 1 (front) harness protector color.
SEF505Y
CAUTION:
Before installing new oxygen sensor, clean exhaust system threads using Oxygen Sensor Thread Cleaner tool
J-43897-18 or J-43897-12 and approved anti-seize lubricant.
©Replace malfunctioning heated oxygen sensor 1 (front).
6 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
©INSPECTION END
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0130, P0150 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(CIRCUIT)
Diagnostic Procedure (Cont'd)
EC-201

6 CHECK HEATED OXYGEN SENSOR 1 (FRONT)
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Set voltmeter probes between ECM terminal 63 (HO2S1 bank 1 right signal) or 62 (HO2S1 bank 2 left signal) and
engine ground.
3. Check the following with engine speed held at 2,000 rpm constant under no load.
SEF967XA
CAUTION:
Discard any heated oxygen sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a
hard surface such as a concrete floor; use a new one.
OK or NG
OK©GO TO 8.
NG©GO TO 7.
7 REPLACE FRONT HEATED OXYGEN SENSOR
1. Turn ignition switch ªOFFº.
2. Check heated oxygen sensor 1 (front) harness protector color.
SEF505Y
CAUTION:
Before installing new oxygen sensor, clean exhaust system threads using Oxygen Sensor Thread Cleaner tool
J-43897-18 or J-43897-12 and approved anti-seize lubricant.
©Replace malfunctioning heated oxygen sensor 1 (front).
8 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
For circuit, refer to ªDTC P0130 (RIGHT BANK 1), P0150 (LEFT BANK 2) HEATED OXYGEN SENSOR 1 (FRONT)
[HO2S1 (FRONT) (BANK 1)/(BANK 2)] (CIRCUIT)º, EC-192.
©INSPECTION END
GI
MA
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LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0131, P0151 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(LEAN SHIFT MONITORING)
Diagnostic Procedure (Cont'd)
EC-209

7 CHECK HEATED OXYGEN SENSOR 1 (FRONT)
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Set voltmeter probes between ECM terminal 63 (HO2S1 bank 1 right signal) or 62 (HO2S1 bank 2 left signal) and
engine ground.
3. Check the following with engine speed held at 2,000 rpm constant under no load.
SEF967XA
CAUTION:
Discard any heated oxygen sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a
hard surface such as a concrete floor; use a new one.
OK or NG
OK©GO TO 9.
NG©GO TO 8.
8 REPLACE HEATED OXYGEN SENSOR 1 (FRONT)
1. Turn ignition switch ªOFFº.
2. Check heated oxygen sensor 1 (front) harness protector color.
SEF505Y
CAUTION:
Before installing new oxygen sensor, clean exhaust system threads using Oxygen Sensor Thread Cleaner tool
J-43897-18 or J-43897-12 and approved anti-seize lubricant.
©Replace malfunctioning heated oxygen sensor 1 (front).
9 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
For circuit, refer to ªDTC P0130 (RIGHT BANK, -B1), P0150 (LEFT BANK, -B2) HEATED OXYGEN SENSOR 1 [HO2S1
(FRONT) (BANK 1)/(BANK 2)] (CIRCUIT)º, EC-192.
©INSPECTION END
GI
MA
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LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
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IDX
DTC P0132, P0152 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(RICH SHIFT MONITORING)
Diagnostic Procedure (Cont'd)
EC-217

6 CHECK HEATED OXYGEN SENSOR 1 (FRONT)
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Set voltmeter probes between ECM terminal 63 (HO2S1 bank 1 right signal) or 62 (HO2S1 bank 2 left signal) and
engine ground.
3. Check the following with engine speed held at 2,000 rpm constant under no load.
SEF967XA
CAUTION:
Discard any heated oxygen sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a
hard surface such as a concrete floor; use a new one.
OK or NG
OK©GO TO 8.
NG©GO TO 7.
7 REPLACE HEATED OXYGEN SENSOR 1 (FRONT)
1. Turn ignition switch ªOFFº.
2. Check heated oxygen sensor 1 (front) harness protector color.
SEF505Y
CAUTION:
Before installing new oxygen sensor, clean exhaust system threads using Oxygen Sensor Thread Cleaner tool
J-43897-18 or J-43897-12 and approved anti-seize lubricant.
©Replace malfunctioning heated oxygen sensor 1 (front).
8 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
©INSPECTION END
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0134, P0154 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(HIGH VOLTAGE)
Diagnostic Procedure (Cont'd)
EC-239

DescriptionNBEC0123SYSTEM DESCRIPTIONNBEC0123S01
Sensor Input Signal to ECMECM func-
tionActuator
Crankshaft position sensor (POS)
Engine speedHeated
oxygen
sensor 1
heater
(front) con-
trolHeated oxygen sensor 1 heat-
ers (front)
Crankshaft position sensor (REF)
The ECM performs ON/OFF control of the heated oxygen sensor 1 heaters (front) corresponding to the engine
speed.
OPERATIONNBEC0123S02
Engine speed rpm Heated oxygen sensor 1 heaters (front)
Above 3,600 OFF
Below 3,600 ON
CONSULT-II Reference Value in Data Monitor
Mode
NBEC0124Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
HO2S1 HTR (B1)
HO2S1 HTR (B2)IEngine speed: Below 3,600 rpm ON
IEngine speed: Above 3,600 rpm OFF
ECM Terminals and Reference ValueNBEC0657Specification 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)
3 L/ORHeated oxygen sensor
1 heater (front) (bank
1)[Engine is running]
IEngine speed is below 3,600 rpm.0 - 1.0V
[Engine is running]
IEngine speed is above 3,600 rpm.BATTERY VOLTAGE
(11 - 14V)
2 R/GHeated oxygen sensor
1 heater (front) (bank
2)[Engine is running]
IEngine speed is below 3,600 rpm.0 - 1.0V
[Engine is running]
IEngine speed is above 3,600 rpm.BATTERY VOLTAGE
(11 - 14V)
DTC P0135, P0155 HEATED OXYGEN SENSOR 1 HEATER (FRONT) (BANK
1)/(BANK 2)
Description
EC-240