2001 INFINITI QX4 wiring

CONSULT-II Reference Value in Data Monitor
Mode ........................................................................585
ECM Terminals and Reference Value .....................585
On Board Diagnosis Logic.......................................586
Possible Cause ........................................................586
DTC Confirmation Procedure ..................................586
Wiring Diagram ........................................................587
Diagnostic Procedure ..............................................588
DTC P1491 VACUUM CUT VALVE BYPASS
VALVE..........................................................................591
Description ...............................................................591
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................591
ECM Terminals and Reference Value .....................591
On Board Diagnosis Logic.......................................592
Possible Cause ........................................................592
DTC Confirmation Procedure ..................................592
Overall Function Check ...........................................593
Wiring Diagram ........................................................594
Diagnostic Procedure ..............................................595
DTC P1605 A/T DIAGNOSIS COMMUNICATION
LINE.............................................................................603
Component Description ...........................................603
On Board Diagnosis Logic.......................................603
Possible Cause ........................................................603
DTC Confirmation Procedure ..................................603
DTC P1706 PARK/NEUTRAL POSITION (PNP)
SWITCH.......................................................................604
Component Description ...........................................604
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................604
ECM Terminals and Reference Value .....................604
On Board Diagnosis Logic.......................................604
Possible Cause ........................................................604
DTC Confirmation Procedure ..................................605
Overall Function Check ...........................................606
Wiring Diagram ........................................................607
Diagnostic Procedure ..............................................608
VARIABLE INDUCTION AIR CONTROL SYSTEM
(VIAS)...........................................................................610
Description ...............................................................610
ECM Terminals and Reference Value ..................... 611
Wiring Diagram ........................................................612
Diagnostic Procedure ..............................................613
INJECTOR...................................................................616
Component Description ...........................................616
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................616
ECM Terminals and Reference Value .....................616
Wiring Diagram ........................................................617Diagnostic Procedure ..............................................618
START SIGNAL...........................................................621
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................621
ECM Terminals and Reference Value .....................621
Wiring Diagram ........................................................622
Diagnostic Procedure ..............................................623
FUEL PUMP.................................................................625
System Description ..................................................625
Component Description ...........................................625
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................625
ECM Terminals and Reference Value .....................626
Wiring Diagram ........................................................627
Diagnostic Procedure ..............................................628
POWER STEERING OIL PRESSURE SWITCH.........634
Component Description ...........................................634
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................634
ECM Terminals and Reference Value .....................634
Wiring Diagram ........................................................635
Diagnostic Procedure ..............................................636
REFRIGERANT PRESSURE SENSOR......................639
Description ...............................................................639
ECM Terminals and Reference Value .....................639
Wiring Diagram ........................................................640
Diagnostic Procedure ..............................................641
ELECTRICAL LOAD SIGNAL.....................................643
ECM Terminals and Reference Value .....................643
Wiring Diagram ........................................................644
Diagnostic Procedure ..............................................645
MIL & DATA LINK CONNECTORS............................648
Wiring Diagram ........................................................648
SERVICE DATA AND SPECIFICATIONS (SDS).......649
Fuel Pressure Regulator..........................................649
Idle Speed and Ignition Timing ................................649
Mass Air Flow Sensor..............................................649
Engine Coolant Temperature Sensor ......................649
Heated Oxygen Sensor 1 Heater (Front) ................649
Fuel Pump ...............................................................649
IACV-AAC Valve ......................................................649
Injector .....................................................................649
Resistor ....................................................................649
Throttle Position Sensor ..........................................650
Calculated Load Value.............................................650
Intake Air Temperature Sensor ................................650
Heated Oxygen Sensor 2 Heater (Rear).................650
Crankshaft Position Sensor (REF) ..........................650
Fuel Tank Temperature Sensor ...............................650
Camshaft Position Sensor (PHASE) .......................650GI
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CONTENTS(Cont'd)
EC-7

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

SEF348N
IWhen measuring ECM signals with a circuit tester, never
allow the two tester probes to contact.
Accidental contact of probes will cause a short circuit and
damage the ECM power transistor.
IDo 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 the ECM
terminals, such as the ground.
SEF099WB
IRegarding model R50, ª-B1º indicates the right bank and
ª-B2º indicates the left bank as shown in the figure.
IBank 1 includes No. 1 cylinder.
Wiring Diagrams and Trouble DiagnosisNBEC0006When you read Wiring diagrams, refer to the following:
IGI-34, ªHOW TO READ WIRING DIAGRAMSº
IEL-9, ªPOWER SUPPLY ROUTINGº for power distribution circuit
When you perform trouble diagnosis, refer to the following:
IGI-38, ªHOW TO FOLLOW TEST GROUP IN TROUBLE DIAGNOSISº
IGI-34, ªHOW TO PERFORM EFFICIENT DIAGNOSIS FOR AN ELECTRICAL INCIDENTº
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PRECAUTIONS
Precautions (Cont'd)
EC-17

25 CHECK HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1) SIGNAL
With CONSULT-II
1. Stop engine.
2. Replace heated oxygen sensor 1 (front) (bank 1).
3. Start engine and warm it up to normal operating temperature.
4. Run engine at approx. 2,000 rpm for approx. 2 minutes under no-load.
5. See ªHO2S1 MNTR (B1)º in ªDATA MONITORº mode.
6. Maintaining engine at 2,000 rpm under no-load (engine is warmed up to normal operating temperature.), check that the
monitor fluctuates between ªLEANº and ªRICHº more than 5 times during 10 seconds.
1 time: RICH®LEAN®RICH
2 times: RICH®LEAN®RICH®LEAN®RICH
Without CONSULT-II
1. Stop engine.
2. Replace heated oxygen sensor 1 (front) (bank 1).
3. Start engine and warm it up to normal operating temperature.
4. Run engine at approx. 2,000 rpm for approx. 2 minutes under no-load.
5. Set voltmeter probe between ECM terminal 63 and ground.
6. Make sure that the voltage fluctuates between 0 - 0.3V and 0.6 - 1.0V more than 5 times during 10 seconds at 2,000
rpm.
1 time: 0 - 0.3V®0.6 - 1.0V®0 - 0.3V
2 times: 0 - 0.3V®0.6 - 1.0V®0 - 0.3V®0.6 - 1.0V®0 - 0.3V
OK or NG
OK©INSPECTION END
NG©GO TO 26.
26 DETECT MALFUNCTIONING PART
Check the following.
ICheck fuel pressure regulator. Refer to EC-40.
ICheck mass air flow sensor and its circuit. Refer to EC-150.
ICheck injector and its circuit. Refer to EC-616.
Clean or replace if necessary.
ICheck engine coolant temperature sensor and its circuit. Refer to EC-187.
ICheck ECM function by substituting another known-good ECM.
(ECM may be the cause of a problem, but this is rarely the case.)
©GO TO 3.
27 CHECK HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1) HARNESS
1. Turn off engine and disconnect battery ground cable.
2. Disconnect ECM harness connector.
3. Disconnect heated oxygen sensor 1 (front) (bank 1) harness connector.
4. Check harness continuity between ECM terminal 63 and heated oxygen sensor 1 (front) RH harness connector terminal
1.
Refer to Wiring Diagram, EC-196.
Continuity should exist.
OK or NG
OK©GO TO 30.
NG©GO TO 29.
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BASIC SERVICE PROCEDURE
Idle Speed/Ignition Timing/Idle Mixture Ratio Adjustment (Cont'd)
EC-53

28 CHECK HEATED OXYGEN SENSOR 1 (FRONT) (BANK 2) HARNESS
1. Turn off engine and disconnect battery ground cable.
2. Disconnect ECM harness connector.
3. Disconnect heated oxygen sensor 1 (front) (bank 2) harness connector.
4. Check harness continuity between ECM terminal 62 and front heated oxygen sensor LH harness connector terminal 1.
Refer to Wiring Diagram, EC-197.
Continuity should exist.
OK or NG
OK©GO TO 30.
NG©GO TO 29.
29 REPAIR OR REPLACE
Repair or replace harness between ECM and heated oxygen sensor 1 (front).
©GO TO 3.
30 PREPARATION FOR ªCOº % CHECK
With CONSULT-II
1. Reconnect ECM harness connector.
2. Turn ignition switch ªONº.
3. Select ªENG COOLANT TEMPº in ªACTIVE TESTº mode.
4. Set ªENG COOLANT TEMPº to 5ÉC (41ÉF) by touching ªDOWNº and ªQdº.
SEF172Y
Without CONSULT-II
1. Disconnect ECM harness connector.
2. Disconnect engine coolant temperature sensor harness connector.
3. Connect a resistor (4.4 kW) between terminals of engine coolant temperature sensor harness connector.
SEF982UA
©GO TO 31.
BASIC SERVICE PROCEDURE
Idle Speed/Ignition Timing/Idle Mixture Ratio Adjustment (Cont'd)
EC-54

MEF036D
IntroductionNBEC0036
SEF233G
SEF234G
The engine has an ECM to control major systems such as fuel
control, ignition control, idle air control system, etc. The ECM
accepts input signals from sensors and instantly drives actuators.
It is essential that both input and output signals are proper and
stable. At the same time, it is important that there are no problems
such as vacuum leaks, fouled spark plugs, or other problems with
the engine.
It is much more difficult to diagnose a problem that occurs intermit-
tently rather than continuously. Most intermittent problems are
caused by poor electric connections or improper wiring. In this
case, careful checking of suspected circuits may help prevent the
replacement of good parts.
A visual check only may not find the cause of the problems. A road
test with CONSULT-II (or GST) or a circuit tester connected should
be performed. Follow the ªWork Flowº on EC-99.
Before undertaking actual checks, take a few minutes to talk with
a customer who approaches with a driveability complaint. The cus-
tomer can supply good information about such problems, espe-
cially intermittent ones. Find out what symptoms are present and
under what conditions they occur. A ªDiagnostic Worksheetº like the
example on next page should be used.
Start your diagnosis by looking for ªconventionalº problems first.
This will help troubleshoot driveability problems on an electronically
controlled engine vehicle.
SEF907L
DIAGNOSTIC WORKSHEETNBEC0036S01There are many operating conditions that lead to the malfunction
of engine components. A good grasp of such conditions can make
trouble-shooting faster and more accurate.
In general, each customer feels differently about a problem. It is
important to fully understand the symptoms or conditions for a
customer complaint.
Utilize a diagnostic worksheet like the one on the next page in order
to organize all the information for troubleshooting.
Some conditions may cause the MIL to come on steady or blink and
DTC to be detected. Examples:
IVehicle ran out of fuel, which caused the engine to misfire.
IFuel filler cap was left off or incorrectly screwed on, allowing
fuel to evaporate into the atmosphere.
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TROUBLE DIAGNOSIS Ð INTRODUCTION
Introduction
EC-97

DESCRIPTION FOR WORK FLOWNBEC0037S01
STEP DESCRIPTION
STEP IGet detailed information about the conditions and the environment when the incident/symptom occurred using
the ªDIAGNOSTIC WORK SHEETº, EC-98.
STEP IIBefore confirming the concern, check and write down (print out using CONSULT-II or GST) the (1st trip) DTC
and the (1st trip) freeze frame data, then erase the DTC and the data. (Refer to EC-72.) The (1st trip) DTC and
the (1st trip) freeze frame data can be used when duplicating the incident at STEP III & IV.
If the incident cannot be verified, perform ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
Study the relationship between the cause, specified by (1st trip) DTC, and the symptom described by the cus-
tomer. (The ªSymptom Matrix Chartº will be useful. See EC-118.)
Also check related service bulletins for information.
STEP IIITry to confirm the symptom and under what conditions the incident occurs.
The ªDIAGNOSTIC WORK SHEETº and the freeze frame data are useful to verify the incident. Connect CON-
SULT-II to the vehicle in DATA MONITOR (AUTO TRIG) mode and check real time diagnosis results.
If the incident cannot be verified, perform ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
If the malfunction code is detected, skip STEP IV and perform STEP V.
STEP IVTry to detect the (1st trip) DTC by driving in (or performing) the ªDTC Confirmation Procedureº. Check and read
the (1st trip) DTC and (1st trip) freeze frame data by using CONSULT-II or GST.
During the (1st trip) DTC verification, be sure to connect CONSULT-II to the vehicle in DATA MONITOR (AUTO
TRIG) mode and check real time diagnosis results.
If the incident cannot be verified, perform ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
In case the ªDTC Confirmation Procedureº is not available, perform the ªOverall Function Checkº instead. The
(1st trip) DTC cannot be displayed by this check, however, this simplified ªcheckº is an effective alternative.
The ªNGº result of the ªOverall Function Checkº is the same as the (1st trip) DTC detection.
STEP VTake the appropriate action based on the results of STEP I through IV.
If the malfunction code is indicated, proceed to TROUBLE DIAGNOSIS FOR DTC PXXXX.
If the normal code is indicated, proceed to the BASIC INSPECTION. (Refer to EC-101.) If CONSULT-II is
available, perform ªDATA MONITOR (SPEC)º mode with CONSULT-II and proceed to the ªTROUBLE DIAGNO-
SIS Ð SPECIFICATION VALUEº, EC-136. (If malfunction is detected, proceed to ªREPAIR REPLACEº.) Then
perform inspections according to the Symptom Matrix Chart. (Refer to EC-118.)
STEP VIIdentify where to begin diagnosis based on the relationship study between symptom and possible causes.
Inspect the system for mechanical binding, loose connectors or wiring damage using (tracing) ªHarness Layoutsº.
Gently shake the related connectors, components or wiring harness with CONSULT-II set in ªDATA MONITOR
(AUTO TRIG)º mode.
Check the voltage of the related ECM terminals or monitor the output data from the related sensors with CON-
SULT-II. Refer to EC-122, 127.
The ªDiagnostic Procedureº in EC section contains a description based on open circuit inspection. A short circuit
inspection is also required for the circuit check in the Diagnostic Procedure. For details, refer to GI-27, ªCircuit
Inspectionº.
Repair or replace the malfunction parts.
If malfunctioning part cannot be detected, perform ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº,
EC-140.
STEP VIIOnce you have repaired the circuit or replaced a component, you need to run the engine in the same conditions
and circumstances which resulted in the customer's initial complaint.
Perform the ªDTC Confirmation Procedureº and confirm the normal code [DTC No. P0000] is detected. If the
incident is still detected in the final check, perform STEP VI by using a different method from the previous one.
Before returning the vehicle to the customer, be sure to erase the unnecessary (already fixed) (1st trip) DTC in
ECM and TCM (Transmission control module). (Refer to EC-72.)
TROUBLE DIAGNOSIS Ð INTRODUCTION
Work Flow (Cont'd)
EC-100

Basic InspectionNBEC0038Precaution:
Perform Basic Inspection without electrical or mechanical
loads applied;
IHeadlamp switch is OFF,
IAir conditioner switch is OFF,
IRear window defogger switch is OFF,
ISteering wheel is in the straight-ahead position, etc.
1 INSPECTION START
1. Check service records for any recent repairs that may indicate a related problem, or a current need for scheduled
maintenance.
2. Open engine hood and check the following:
IHarness connectors for improper connections
IVacuum hoses for splits, kinks and improper connections
IWiring for improper connections, pinches and cuts
IAir cleaner clogging
IHoses and ducts for leaks
SEF983U
©GO TO 2.
2 CHECK THROTTLE OPENER OPERATION-I
Confirm that there is a clearance between throttle drum and stopper.
SEF950Y
OK or NG
OK©GO TO 4.
NG©GO TO 3.
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TROUBLE DIAGNOSIS Ð BASIC INSPECTION
Basic Inspection
EC-101