2001 INFINITI QX4 check engine

GENERAL INFORMATION
SECTION
GI
CONTENTS
PRECAUTIONS...............................................................3
Precautions ..................................................................3
PRECAUTIONS FOR SUPPLEMENTAL
RESTRAINT SYSTEM (SRS)²AIR BAG²AND
²SEAT BELT PRE-TENSIONER²
.................................3
PRECAUTIONS FOR IVIS (INFINITI VEHICLE
IMMOBILIZER SYSTEM - NATS)
.................................3
PRECAUTIONS FOR INFINITI COMMUNICATOR
(IVCS)
.......................................................................4
GENERAL PRECAUTIONS.........................................5
PRECAUTIONS FOR MULTIPORT FUEL
INJECTION SYSTEM OR ENGINE CONTROL
SYSTEM
...................................................................6
PRECAUTIONS FOR THREE WAY CATALYST...........6
PRECAUTIONS FOR HOSES.....................................7
PRECAUTIONS FOR ENGINE OILS...........................8
PRECAUTIONS FOR FUEL........................................8
PRECAUTIONS FOR AIR CONDITIONING..................8
HOW TO USE THIS MANUAL........................................9
HOW TO READ WIRING DIAGRAMS.......................... 11
Sample/Wiring Diagram - EXAMPL - ........................ 11
OPTIONAL SPLICE..................................................12
Description .................................................................13
CONNECTOR SYMBOLS.........................................15
HARNESS INDICATION...........................................16
COMPONENT INDICATION......................................16
SWITCH POSITIONS...............................................16
DETECTABLE LINES AND NON-DETECTABLE
LINES
.....................................................................17
MULTIPLE SWITCH.................................................18
REFERENCE AREA.................................................19
HOW TO CHECK TERMINAL.......................................21
Connector and Terminal Pin Kit.................................21
How to Probe Connectors .........................................21
PROBING FROM HARNESS SIDE............................21
PROBING FROM TERMINAL SIDE...........................21
How to Check Enlarged Contact Spring of
Terminal .....................................................................22
Waterproof Connector Inspection ..............................23
RUBBER SEAL INSPECTION...................................23
WIRE SEAL INSPECTION........................................23Terminal Lock Inspection ...........................................23
HOW TO PERFORM EFFICIENT DIAGNOSIS
FOR AN ELECTRICAL INCIDENT...............................24
Work Flow ..................................................................24
Incident Simulation Tests ...........................................25
INTRODUCTION......................................................25
VEHICLE VIBRATION..............................................25
HEAT SENSITIVE....................................................26
FREEZING..............................................................26
WATER INTRUSION................................................27
ELECTRICAL LOAD.................................................27
COLD OR HOT START UP.......................................27
Circuit Inspection .......................................................27
INTRODUCTION......................................................27
TESTING FOR²OPENS²IN THE CIRCUIT................28
TESTING FOR²SHORTS²IN THE CIRCUIT..............29
GROUND INSPECTION...........................................30
VOLTAGE DROP TESTS..........................................30
CONTROL UNIT CIRCUIT TEST...............................32
HOW TO FOLLOW TROUBLE DIAGNOSIS................34
How to Follow Test Groups in Trouble Diagnosis .....35
Key to Symbols Signifying Measurements or
Procedures.................................................................36
CONSULT-II CHECKING SYSTEM...............................38
Function and System Application ..............................38
Nickel Metal Hydride Battery Replacement...............39
Checking Equipment..................................................39
CONSULT-II Data Link Connector (DLC) Circuit ......40
INSPECTION PROCEDURE.....................................40
IDENTIFICATION INFORMATION................................41
Model Variation ..........................................................41
PREFIX AND SUFFIX DESIGNATIONS.....................41
Identification Number .................................................41
VEHICLE IDENTIFICATION NUMBER
ARRANGEMENT
.....................................................42
IDENTIFICATION PLATE..........................................42
ENGINE SERIAL NUMBER.......................................43
AUTOMATIC TRANSMISSION NUMBER...................43
TRANSFER SERIAL NUMBER..................................43
Dimensions ................................................................43
MA
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IClean all disassembled parts in the designated liquid or solvent
prior to inspection or assembly.
IReplace oil seals, gaskets, packings, O-rings, locking washers,
cotter pins, self-locking nuts, etc. with new ones.
IReplace inner and outer races of tapered roller bearings and
needle bearings as a set.
IArrange the disassembled parts in accordance with their
assembled locations and sequence.
IDo not touch the terminals of electrical components which use
microcomputers (such as ECMs).
Static electricity may damage internal electronic components.
IAfter disconnecting vacuum or air hoses, attach a tag to indi-
cate the proper connection.
IUse only the fluids and lubricants specified in this manual.
IUse approved bonding agent, sealants or their equivalents
when required.
IUse tools and recommended special tools where specified for
safe and efficient service repairs.
IWhen repairing the fuel, oil, water, vacuum or exhaust
systems, check all affected lines for leaks.
IDispose of drained oil or the solvent used for cleaning parts in
an appropriate manner.
WARNING:
To prevent ECM from storing the diagnostic trouble codes, do
not carelessly disconnect the harness connectors which are
related to the engine control system and TCM (Transmission
Control Module) system. The connectors should be discon-
nected only when working according to the WORK FLOW of
TROUBLE DIAGNOSES in EC and AT sections.
SGI787
PRECAUTIONS FOR MULTIPORT FUEL INJECTION
SYSTEM OR ENGINE CONTROL SYSTEM
NBGI0001S03IBefore connecting or disconnecting any harness connector for
the multiport fuel injection system or ECM (Engine Control
Module):
Turn ignition switch to OFF position.
Disconnect negative battery terminal.
Otherwise, there may be damage to ECM.
IBefore disconnecting pressurized fuel line from fuel pump to
injectors, be sure to release fuel pressure.
IBe careful not to jar components such as ECM and mass air
flow sensor.
PRECAUTIONS FOR THREE WAY CATALYSTNBGI0001S04If a large amount of unburned fuel flows into the catalyst, the cata-
lyst temperature will be excessively high. To prevent this, follow the
instructions below:
IUse unleaded gasoline only. Leaded gasoline will seriously
damage the three way catalyst.
IWhen checking for ignition spark or measuring engine
compression, make tests quickly and only when necessary.
IDo not run engine when the fuel tank level is low, otherwise the
engine may misfire causing damage to the catalyst.
PRECAUTIONS
Precautions (Cont'd)
GI-6

PRECAUTIONS FOR ENGINE OILSNBGI0001S05Prolonged and repeated contact with used engine oil may cause
skin cancer. Try to avoid direct skin contact with used oil.
If skin contact is made, wash thoroughly with soap or hand cleaner
as soon as possible.
Health Protection PrecautionsNBGI0001S0501IAvoid prolonged and repeated contact with oils, particularly
used engine oils.
IWear protective clothing, including impervious gloves where
practicable.
IDo not put oily rags in pockets.
IAvoid contaminating clothes, particularly underpants, with oil.
IHeavily soiled clothing and oil-impregnated footwear should
not be worn. Overalls must be cleaned regularly.
IFirst Aid treatment should be obtained immediately for open
cuts and wounds.
IUse barrier creams, applying them before each work period, to
help the removal of oil from the skin.
IWash with soap and water to ensure all oil is removed (skin
cleansers and nail brushes will help). Preparations containing
lanolin replace the natural skin oils which have been removed.
IDo not use gasoline, kerosine, diesel fuel, gas oil, thinners or
solvents for cleaning skin.
IIf skin disorders develop, obtain medical advice without delay.
IWhere practicable, degrease components prior to handling.
IWhere there is a risk of eye contact, eye protection should be
worn, for example, chemical goggles or face shields; in addi-
tion an eye wash facility should be provided.
Environmental Protection PrecautionsNBGI0001S0502Burning used engine oil in small space heaters or boilers can be
recommended only for units of approved design. The heating sys-
tem must meet the requirements of HM Inspectorate of Pollution for
small burners of less than 0.4 MW. If in doubt check with the
appropriate local authority and/or manufacturer of the approved
appliance.
Dispose of used oil and used oil filters through authorized waste
disposal contractors to licensed waste disposal sites, or to the
waste oil reclamation trade. If in doubt, contact the local authority
for advice on disposal facilities.
It is illegal to pour used oil on to the ground, down sewers or drains,
or into water courses.
The regulations concerning pollution vary between regions.
PRECAUTIONS FOR FUELNBGI0001S06Use unleaded gasoline with an octane rating of at least 87 AKI
(Anti-Knock Index) number (research octane number 91).
CAUTION:
Do not use leaded gasoline. Using leaded gasoline will dam-
age the three way catalyst.
Using a fuel other than that specified could adversely affect
the emission control devices and systems, and could also
affect the warranty coverage validity.
PRECAUTIONS FOR AIR CONDITIONINGNBGI0001S07Use an approved refrigerant recovery unit any time the air condi-
tioning system must be discharged. Refer to HA-144, ªHFC-134a
(R-134a) Service Procedureº for specific instructions.
PRECAUTIONS
Precautions (Cont'd)
GI-8

ISERVICE DATA AND SPECIFICATIONSare contained at the end of each section for quick reference of
data.
IThe followingSYMBOLS AND ABBREVIATIONSare used:
SYMBOL ABBREVIATION SYMBOL ABBREVIATION
Tightening torque
2WD2-Wheel Drive
Should be lubricated with grease. Unless oth-
erwise indicated, use recommended multi-pur-
pose grease.A/CAir Conditioner
Should be lubricated with oil. P/S Power Steering
Sealing point SST Special Service Tools
Checking point SAE Society of Automotive Engineers, Inc.
Always replace after every disassembly. ATF Automatic Transmission Fluid
qP
Apply petroleum jelly.
D1Drive range 1st gear
Apply ATF. D2Drive range 2nd gear
HSelect with proper thickness. D
3Drive range 3rd gear
IAdjustment is required. D
4Drive range 4th gear
SDS Service Data and Specifications OD Overdrive
LH, RH Left-Hand, Right-Hand 2
22nd range 2nd gear
FR, RR Front, Rear 2
12nd range 1st gear
M/T Manual Transaxle/Transmission 1
21st range 2nd gear
A/T Automatic Transaxle/Transmission 1
11st range 1st gear
,
4WD4-Wheel Drive
HOW TO USE THIS MANUAL
GI-10

NBGI0004
Work FlowNBGI0004S01
SGI838
STEP DESCRIPTION
STEP 1 Get detailed information about the conditions and the environment when the incident occurred.
The following are key pieces of information required to make a good analysis:
WHATVehicle Model, Engine, Transmission and the System (i.e. Radio).
WHENDate, Time of Day, Weather Conditions, Frequency.
WHERERoad Conditions, Altitude and Traffic Situation.
HOWSystem Symptoms, Operating Conditions (Other Components Interaction).
Service History and if any After Market Accessories have been installed.
STEP 2 Operate the system, road test if necessary.
Verify the parameter of the incident.
If the problem can not be duplicated, refer to ªIncident Simulation Testsº next page.
STEP 3 Get the proper diagnosis materials together including:
POWER SUPPLY ROUTING
System Operation Descriptions
Applicable Service Manual Sections
Check for any Service Bulletin.
Identify where to begin diagnosis based upon your knowledge of the system operation and the cus-
tomer comments.
STEP 4 Inspect the system for mechanical binding, loose connectors or wiring damage.
Determine which circuits and components are involved and diagnose using the Power Supply Routing
and Harness Layouts.
STEP 5 Repair or replace the incident circuit or component.
STEP 6 Operate the system in all modes. Verify the system works properly under all conditions. Make sure you
have not inadvertently created a new incident during your diagnosis or repair steps.
HOW TO PERFORM EFFICIENT DIAGNOSIS FOR AN ELECTRICAL INCIDENT
Work Flow
GI-24

Incident Simulation TestsNBGI0004S02INTRODUCTIONNBGI0004S0201Sometimes the symptom is not present when the vehicle is brought
in for service. If possible, re-create the conditions present at the
time of the incident. Doing so may help avoid a No Trouble Found
Diagnosis. The following section illustrates ways to simulate the
conditions/environment under which the owner experiences an
electrical incident.
The section is broken into the six following topics:
IVehicle vibration
IHeat sensitive
IFreezing
IWater intrusion
IElectrical load
ICold or hot start up
Get a thorough description of the incident from the customer. It is
important for simulating the conditions of the problem.
VEHICLE VIBRATIONNBGI0004S0202The problem may occur or become worse while driving on a rough
road or when engine is vibrating (idle with A/C on). In such a case,
you will want to check for a vibration related condition. Refer to the
illustration below.
Connectors & Harness
Determine which connectors and wiring harness would affect the
electrical system you are inspecting.Gentlyshake each connec-
tor and harness while monitoring the system for the incident you
are trying to duplicate. This test may indicate a loose or poor elec-
trical connection.
Hint
Connectors can be exposed to moisture. It is possible to get a thin
film of corrosion on the connector terminals. A visual inspection
may not reveal this without disconnecting the connector. If the
problem occurs intermittently, perhaps the problem is caused by
corrosion. It is a good idea to disconnect, inspect and clean the
terminals on related connectors in the system.
Sensors & Relays
Gentlyapply a slight vibration to sensors and relays in the system
you are inspecting.
This test may indicate a loose or poorly mounted sensor or relay.
SGI839
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HOW TO PERFORM EFFICIENT DIAGNOSIS FOR AN ELECTRICAL INCIDENT
Incident Simulation Tests
GI-25

Engine Compartment
There are several reasons a vehicle or engine vibration could
cause an electrical complaint. Some of the things to check for are:
IConnectors not fully seated.
IWiring harness not long enough and is being stressed due to
engine vibrations or rocking.
IWires laying across brackets or moving components.
ILoose, dirty or corroded ground wires.
IWires routed too close to hot components.
To inspect components under the hood, start by verifying the integ-
rity of ground connections. (Refer to GROUND INSPECTION
described later.) First check that the system is properly grounded.
Then check for loose connection bygently shakingthe wiring or
components as previously explained. Using the wiring diagrams
inspect the wiring for continuity.
Behind The Instrument Panel
An improperly routed or improperly clamped harness can become
pinched during accessory installation. Vehicle vibration can aggra-
vate a harness which is routed along a bracket or near a screw.
Under Seating Areas
An unclamped or loose harness can cause wiring to be pinched by
seat components (such as slide guides) during vehicle vibration. If
the wiring runs under seating areas, inspect wire routing for pos-
sible damage or pinching.
SGI842
HEAT SENSITIVENBGI0004S0203The owner's problem may occur during hot weather or after car has
sat for a short time. In such cases you will want to check for a heat
sensitive condition.
To determine if an electrical component is heat sensitive, heat the
component with a heat gun or equivalent.
Do not heat components above 60ÉC (140ÉF).If incident occurs
while heating the unit, either replace or properly insulate the com-
ponent.
SGI843
FREEZINGNBGI0004S0204The customer may indicate the incident goes away after the car
warms up (winter time). The cause could be related to water freez-
ing somewhere in the wiring/electrical system.
There are two methods to check for this. The first is to arrange for
the owner to leave his car overnight. Make sure it will get cold
enough to demonstrate his complaint. Leave the car parked out-
side overnight. In the morning, do a quick and thorough diagnosis
of those electrical components which could be affected.
HOW TO PERFORM EFFICIENT DIAGNOSIS FOR AN ELECTRICAL INCIDENT
Incident Simulation Tests (Cont'd)
GI-26

Key to Symbols Signifying Measurements or
Procedures
NBGI0005S02
Symbol Symbol explanation Symbol Symbol explanation
Check after disconnecting the con-
nector to be measured.Procedure with Generic Scan Tool
(GST, OBD-II scan tool)
Check after connecting the connec-
tor to be measured.Procedure without CONSULT-II or
GST
Insert key into ignition switch.A/C switch is ªOFFº.
Remove key from ignition switch.A/C switch is ªONº.
Turn ignition switch to ªOFFº posi-
tion.REC switch is ªONº.
Turn ignition switch to ªONº position.REC switch is ªOFFº.
Turn ignition switch to ªSTARTº posi-
tion.Fan switch is ªONº. (At any position
except for ªOFFº position)
Turn ignition switch from ªOFFº to
ªACCº position.Fan switch is ªOFFº.
Turn ignition switch from ªACCº to
ªOFFº position.Apply positive voltage from battery
with fuse directly to components.
Turn ignition switch from ªOFFº to
ªONº position.Drive vehicle.
Turn ignition switch from ªONº to
ªOFFº position.Disconnect battery negative cable.
Do not start engine, or check with
engine stopped.Depress brake pedal.
Start engine, or check with engine
running.Release brake pedal.
Apply parking brake.Depress accelerator pedal.
Release parking brake.Release accelerator pedal.
HOW TO FOLLOW TROUBLE DIAGNOSIS
Key to Symbols Signifying Measurements or Procedures
GI-36