2001 INFINITI QX4 ESP

CONSULT-II Reference Value in Data Monitor
Mode ........................................................................231
ECM Terminals and Reference Value .....................231
On Board Diagnosis Logic.......................................232
Possible Cause ........................................................232
DTC Confirmation Procedure ..................................232
Wiring Diagram ........................................................234
Diagnostic Procedure ..............................................236
DTC P0135, P0155 HEATED OXYGEN SENSOR 1
HEATER (FRONT) (BANK 1)/(BANK 2).....................240
Description ...............................................................240
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................240
ECM Terminals and Reference Value .....................240
On Board Diagnosis Logic.......................................241
Possible Cause ........................................................241
DTC Confirmation Procedure ..................................241
Wiring Diagram ........................................................242
Diagnostic Procedure ..............................................244
DTC P0137, P0157 HEATED OXYGEN SENSOR 2
(REAR) (BANK 1)/(BANK 2) (MIN. VOLTAGE
MONITORING).............................................................247
Component Description ...........................................247
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................247
ECM Terminals and Reference Value .....................247
On Board Diagnosis Logic.......................................247
Possible Cause ........................................................248
DTC Confirmation Procedure ..................................248
Overall Function Check ...........................................248
Wiring Diagram ........................................................250
Diagnostic Procedure ..............................................252
DTC P0138, P0158 HEATED OXYGEN SENSOR 2
(REAR) (BANK 1)/(BANK 2) (MAX. VOLTAGE
MONITORING).............................................................257
Component Description ...........................................257
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................257
ECM Terminals and Reference Value .....................257
On Board Diagnosis Logic.......................................257
Possible Cause ........................................................258
DTC Confirmation Procedure ..................................258
Overall Function Check ...........................................258
Wiring Diagram ........................................................260
Diagnostic Procedure ..............................................262
DTC P0139, P0159 HEATED OXYGEN SENSOR 2
(REAR) (BANK 1)/(BANK 2) (RESPONSE
MONITORING).............................................................267
Component Description ...........................................267
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................267
ECM Terminals and Reference Value .....................267On Board Diagnosis Logic.......................................267
Possible Cause ........................................................268
DTC Confirmation Procedure ..................................268
Overall Function Check ...........................................268
Wiring Diagram ........................................................270
Diagnostic Procedure ..............................................272
DTC P0140, P0160 HEATED OXYGEN SENSOR 2
(REAR) (BANK 1)/(BANK 2) (HIGH VOLTAGE)........277
Component Description ...........................................277
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................277
ECM Terminals and Reference Value .....................277
On Board Diagnosis Logic.......................................277
Possible Cause ........................................................278
DTC Confirmation Procedure ..................................278
Overall Function Check ...........................................278
Wiring Diagram ........................................................280
Diagnostic Procedure ..............................................282
DTC P0141, P0161 HEATED OXYGEN SENSOR 2
HEATER (REAR) (BANK 1)/(BANK 2).......................286
Description ...............................................................286
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................286
ECM Terminals and Reference Value .....................286
On Board Diagnosis Logic.......................................287
Possible Cause ........................................................287
DTC Confirmation Procedure ..................................287
Wiring Diagram ........................................................289
Diagnostic Procedure ..............................................291
DTC P0171 (RIGHT, -B1), P0174 (LEFT, -B2)
FUEL INJECTION SYSTEM FUNCTION (LEAN).......294
On Board Diagnosis Logic.......................................294
Possible Cause ........................................................294
DTC Confirmation Procedure ..................................294
Wiring Diagram ........................................................296
Diagnostic Procedure ..............................................298
DTC P0172 (RIGHT, -B1), P0175 (LEFT, -B2)
FUEL INJECTION SYSTEM FUNCTION (RICH)........302
On Board Diagnosis Logic.......................................302
Possible Cause ........................................................302
DTC Confirmation Procedure ..................................302
Wiring Diagram ........................................................304
Diagnostic Procedure ..............................................306
DTC P0180 FUEL TANK TEMPERATURE
SENSOR......................................................................309
Component Description ...........................................309
On Board Diagnosis Logic.......................................309
Possible Cause ........................................................309
DTC Confirmation Procedure ..................................310
Wiring Diagram ........................................................ 311
Diagnostic Procedure ..............................................312GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
CONTENTS(Cont'd)
EC-3

Supplemental Restraint System (SRS) ªAIR
BAGº and ªSEAT BELT PRE-TENSIONERº
NBEC0002The Supplemental Restraint System such as ªAIR BAGº and ªSEAT BELT PRE-TENSIONERº used along with
a seat belt, helps to reduce the risk or severity of injury to the driver and front passenger for certain types of
collision. The SRS system composition which is available to INFINITI QX4 is as follows:
IFor a frontal collision
The Supplemental Restraint System consists of driver air bag module (located in the center of the steer-
ing wheel), front passenger air bag module (located on the instrument panel on passenger side), seat belt
pre-tensioners, a diagnosis sensor unit, warning lamp, wiring harness and spiral cable.
IFor a side collision
The Supplemental Restraint System consists of front side air bag module (located in the outer side of front
seat), satellite sensor, diagnosis sensor unit (one of components of air bags for a frontal collision), wiring
harness, warning lamp (one of components of air bags for a frontal collision).
Information necessary to service the system safely is included in theRS sectionof this Service Manual.
WARNING:
ITo avoid rendering the SRS inoperative, which could increase the risk of personal injury or death
in the event of a collision which would result in air bag inflation, all maintenance must be performed
by an authorized INFINITI dealer.
IImproper maintenance, including incorrect removal and installation of the SRS, can lead to per-
sonal injury caused by unintentional activation of the system. For removal of Spiral Cable and Air
Bag Module, see the RS section.
IDo not use electrical test equipment on any circuit related to the SRS unless instructed to in this
Service Manual. Spiral cable and wiring harnesses covered with yellow insulation tape either just
before the harness connectors or for the complete harness are related to the SRS.
Precautions for On Board Diagnostic (OBD)
System of Engine and A/T
NBEC0003The ECM has an on board diagnostic system. It will light up the malfunction indicator lamp (MIL) to warn the
driver of a malfunction causing emission deterioration.
CAUTION:
IBe sure to turn the ignition switch OFF and disconnect the negative battery terminal before any
repair or inspection work. The open/short circuit of related switches, sensors, solenoid valves, etc.
will cause the MIL to light up.
IBe sure to connect and lock the connectors securely after work. A loose (unlocked) connector will
cause the MIL to light up due to the open circuit. (Be sure the connector is free from water, grease,
dirt, bent terminals, etc.)
ICertain systems and components, especially those related to OBD, may use a new style slide-
locking type harness connector. For description and how to disconnect, refer to EL-6, ªHARNESS
CONNECTOR (SLIDE-LOCKING TYPE)º.
IBe sure to route and secure the harnesses properly after work. The interference of the harness with
a bracket, etc. may cause the MIL to light up due to the short circuit.
IBe sure to connect rubber tubes properly after work. A misconnected or disconnected rubber tube
may cause the MIL to light up due to the malfunction of the fuel injection system, etc.
IBe sure to erase the unnecessary malfunction information (repairs completed) from the ECM and
TCM (Transmission control module) before returning the vehicle to the customer.
PRECAUTIONS
Supplemental Restraint System (SRS) ªAIR BAGº and ªSEAT BELT PRE-TENSIONERº
EC-14

INSPECTION PROCEDURE=NBEC0028S02
1 INSPECTION START
1. Visually check the following:
IAir cleaner clogging
IHoses and ducts for leaks
IElectrical connectors
IGasket
IThrottle valve and throttle position sensor operation
2. Start engine and warm it up until engine coolant temperature indicator points to the middle of gauge.
Ensure engine stays below 1,000 rpm.
SEF976U
3. Open engine hood and run engine at about 2,000 rpm for about 2 minutes under no-load.
SEF977U
4. Make sure that no DTC is displayed with CONSULT-II or GST.
OK or NG
OK©GO TO 3.
NG©GO TO 2.
2 REPAIR OR REPLACE
Repair or replace components as necessary according to corresponding ªDiagnostic Procedureº.
©GO TO 3.
3 CHECK TARGET IDLE SPEED
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select ªENG SPEEDº in ªDATA MONITORº mode with CONSULT-II.
3. Check idle speed.
750±50 rpm (in ªPº or ªNº position)
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Check idle speed.
750±50 rpm (in ªPº or ªNº position)
OK or NG
OK©GO TO 12.
NG©GO TO 4.
BASIC SERVICE PROCEDURE
Idle Speed/Ignition Timing/Idle Mixture Ratio Adjustment (Cont'd)
EC-46

SRT Item=NBEC0031S0310The table below shows required self-diagnostic items to set the SRT to ªCMPLTº.
SRT item
(CONSULT-II indica-
tion)Perfor-
mance Pri-
ority*Required self-diagnostic items to set the SRT to ªCMPLTºCorresponding
DTC No.
CATALYST 3 Three way catalyst function P0420, P0430
EVAP SYSTEM 2 EVAP control system (small leak) (negative pressure) P0440
3 EVAP control system (very small leak) (negative pressure)/
(positive pressure)P1441
3 EVAP control system purge flow monitoring P1447
O2 SENSOR 3 Heated oxygen sensor 1 (front) (circuit) P0130, P0150
Heated oxygen sensor 1 (front) (lean shift monitoring) P0131, P0151
Heated oxygen sensor 1 (front) (rich shift monitoring) P0132, P0152
Heated oxygen sensor 1 (front) (response monitoring) P0133, P0153
Heated oxygen sensor 1 (front) (high voltage) P0134, P0154
Heated oxygen sensor 2 (rear) (min. voltage monitoring) P0137, P0157
Heated oxygen sensor 2 (rear) (max. voltage monitoring) P0138, P0158
Heated oxygen sensor 2 (rear) (response monitoring) P0139, P0159
Heated oxygen sensor 2 (rear) (high voltage) P0140, P0160
O2 SEN HEATER 3 Heated oxygen sensor 1 heater (front) P0135, P0155
Heated oxygen sensor 2 heater (rear) P0141, P0161
*: If completion of several SRTs is required, perform driving patterns (DTC confirmation procedure), one by one based on the priority
for models with CONSULT-II.
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
Emission-related Diagnostic Information (Cont'd)
EC-62

SRT Set Timing=NBEC0031S0311SRT is set as ªCMPLTº after self-diagnosis has been performed one or more times. Completion of SRT is done
regardless of whether the result is OK or NG. The set timing is different between OK and NG results and is
shown in the table below.
Self-diagnosis resultExample
DiagnosisIgnition cycle
+ON,OFF+ON,OFF+ON,OFF+ON,
All OK Case 1 P0400 OK (1) Ð (1) OK (2) Ð (2)
P0402 OK (1) Ð (1) Ð (1) OK (2)
P1402 OK (1) OK (2) Ð (2) Ð (2)
SRT of EGR ªCMPLTº ªCMPLTº ªCMPLTº ªCMPLTº
Case 2 P0400 OK (1) Ð (1) Ð (1) Ð (1)
P0402 Ð (0) Ð (0) OK (1) Ð (1)
P1402 OK (1) OK (2) Ð (2) Ð (2)
SRT of EGR ªINCMPº ªINCMPº ªCMPLTº ªCMPLTº
NG exists Case 3 P0400 OK OK Ð Ð
P0402 Ð Ð Ð Ð
P1402 NG Ð NGNG
(Consecutive NG)
(1st trip)
DTC1st trip DTC Ð 1st trip DTCDTC
(= MIL ªONº)
SRT of EGR ªINCMPº ªINCMPº ªINCMPº ªCMPLTº
OK: Self-diagnosis is carried out and the result is OK.
NG: Self-diagnosis is carried out and the result is NG.
Ð: Self-diagnosis is not carried out.
When all SRT related self-diagnoses showed OK results in a single cycle (Ignition OFF-ON-OFF), the SRT
will indicate ªCMPLTº.,Case 1 above
When all SRT related self-diagnoses showed OK results through several different cycles, the SRT will indi-
cate ªCMPLTº at the time the respective self-diagnoses have at least one OK result.,Case 2 above
If one or more SRT related self-diagnoses showed NG results in 2 consecutive cycles, the SRT will also indi-
cate ªCMPLTº.,Case 3 above
The table above shows that the minimum number of cycles for setting SRT as ªINCMPº is one (1) for each
self-diagnosis (Case1&2)ortwo(2)foroneofself-diagnoses (Case 3). However, in preparation for the state
emissions inspection, it is unnecessary of each self-diagnosis to be executed twice (Case 3) for the following
reasons:
IThe SRT will indicate ªCMPLTº at the time the respective self-diagnoses have one (1) OK result.
IThe emissions inspection requires ªCMPLTº of the SRT only with OK self-diagnosis results.
IWhen, during SRT driving pattern, 1st trip DTC (NG) is detected prior to ªCMPLTº of SRT, the self-diag-
nosis memory must be erased from ECM after repair.
IIf the 1st trip DTC is erased, all the SRT will indicate ªINCMPº.
NOTE:
SRT can be set as ªCMPLTº together with the DTC(s). Therefore, DTC check must always be carried out prior
to the state emission inspection even though the SRT indicates ªCMPLTº.
SRT Service ProcedureNBEC0031S0312If a vehicle has failed the state emissions inspection due to one or more SRT items indicating ªINCMPº, review
the flowchart diagnostic sequence on the next page.
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
Emission-related Diagnostic Information (Cont'd)
EC-63

SEF949Z
How to Set SRT CodeNBEC0031S0302To set all SRT codes, self-diagnosis for the items indicated above must be performed one or more times. Each
diagnosis may require a long period of actual driving under various conditions.
With CONSULT-II
Perform corresponding DTC Confirmation Procedure one by one based on ªPerformance Priorityº in the table
on EC-62.
Without CONSULT-II
The most efficient driving pattern in which SRT codes can be properly set is explained on the next page. The
driving pattern should be performed one or more times to set all SRT codes.
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
Emission-related Diagnostic Information (Cont'd)
EC-65

DTC Work Support ModeNBEC0034S0802
Test mode Test item Condition Reference page
EVAPORATIVE SYSTEMEVAP SML LEAK P0440
Refer to corresponding
trouble diagnosis for
DTC.EC-352
EVAP VERY SML LEAK P1441 EC-526
PURG VOL CN/V P1444 EC-541
PURGE FLOW P1447 EC-561
VC CUT/V BP/V P1491 EC-591
HEATED OXYGEN SEN-
SOR 1 (FRONT)HO2S1 (B1) P0130 EC-192
HO2S1 (B1) P0131 EC-202
HO2S1 (B1) P0132 EC-210
HO2S1 (B1) P0133 EC-218
HO2S1 (B2) P0150 EC-192
HO2S1 (B2) P0151 EC-202
HO2S1 (B2) P0152 EC-210
HO2S1 (B2) P0153 EC-218
HEATED OXYGEN SEN-
SOR 2 (REAR)HO2S2 (B1) P0137 EC-247
HO2S2 (B1) P0138 EC-257
HO2S2 (B1) P0139 EC-267
HO2S2 (B2) P0157 EC-247
HO2S2 (B2) P0158 EC-257
HO2S2 (B2) P0159 EC-267
SEF705Y
SEF707X
REAL TIME DIAGNOSIS IN DATA MONITOR MODE
(RECORDING VEHICLE DATA)
NBEC0034S10CONSULT-II has two kinds of triggers and they can be selected by
touching ªSETTINGº in ªDATA MONITORº mode.
1) ªAUTO TRIGº (Automatic trigger):
IThe malfunction will be identified on the CONSULT-II screen in
real time.
In other words, DTC/1st trip DTC and malfunction item will be
displayed if the malfunction is detected by ECM.
At the moment a malfunction is detected by ECM, ªMONITORº
in ªDATA MONITORº screen is changed to ªRecording Data ...
xx%º as shown at left, and the data after the malfunction detec-
tion is recorded. Then when the percentage reached 100%,
ªREAL-TIME DIAGº screen is displayed. If ªSTOPº is touched
on the screen during ª Recording Data ... xx%º, ªREAL-TIME
DIAGº screen is also displayed.
The recording time after the malfunction detection and the
recording speed can be changed by ªTRIGGER POINTº and
ªRecording Speedº. Refer to CONSULT-II OPERATION
MANUAL.
2) ªMANU TRIGº (Manual trigger):
IDTC/1st trip DTC and malfunction item will not be displayed
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
CONSULT-II (Cont'd)
EC-93

automatically on CONSULT-II screen even though a malfunc-
tion is detected by ECM.
DATA MONITOR can be performed continuously even though
a malfunction is detected.
Use these triggers as follows:
1) ªAUTO TRIGº
IWhile trying to detect the DTC/1st trip DTC by performing the
ªDTC Confirmation Procedureº, be sure to select to ªDATA
MONITOR (AUTO TRIG)º mode. You can confirm the malfunc-
tion at the moment it is detected.
IWhile narrowing down the possible causes, CONSULT-II
should be set in ªDATA MONITOR (AUTO TRIG)º mode, espe-
cially in case the incident is intermittent.
When you are inspecting the circuit by gently shaking (or twist-
ing) the suspicious connectors, components and harness in
the ªDTC Confirmation Procedureº, the moment a malfunction
is found the DTC/1st trip DTC will be displayed. (Refer to
GI-36, ªIncident Simulation Testsº.)
2) ªMANU TRIGº
IIf the malfunction is displayed as soon as ªDATA MONITORº
is selected, reset CONSULT-II to ªMANU TRIGº. By selecting
ªMANU TRIGº you can monitor and store the data. The data
can be utilized for further diagnosis, such as a comparison with
the value for the normal operating condition.
SEF714Y
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
CONSULT-II (Cont'd)
EC-94