2001 INFINITI QX4 OBD port

ENGINE CONTROL SYSTEM
SECTION
EC
CONTENTS
TROUBLE DIAGNOSIS - INDEX....................................8
Alphabetical & P No. Index for DTC ...........................8
PRECAUTIONS.............................................................14
Supplemental Restraint System (SRS)²AIR
BAG²and²SEAT BELT PRE-TENSIONER².............14
Precautions for On Board Diagnostic (OBD)
System of Engine and A/T.........................................14
Engine Fuel & Emission Control System ..................15
Precautions ................................................................16
Wiring Diagrams and Trouble Diagnosis ...................17
PREPARATION.............................................................18
Special Service Tools ................................................18
Commercial Service Tools .........................................18
ENGINE AND EMISSION CONTROL OVERALL
SYSTEM.........................................................................20
Engine Control Component Parts Location ...............20
Circuit Diagram ..........................................................24
System Diagram ........................................................25
Vacuum Hose Drawing ..............................................26
System Chart .............................................................27
ENGINE AND EMISSION BASIC CONTROL
SYSTEM DESCRIPTION...............................................28
Multiport Fuel Injection (MFI) System .......................28
Electronic Ignition (EI) System ..................................30
Air Conditioning Cut Control ......................................31
Fuel Cut Control (at no load & high engine
speed) ........................................................................32
Evaporative Emission System ...................................32
Positive Crankcase Ventilation ..................................38
BASIC SERVICE PROCEDURE...................................39
Fuel Pressure Release ..............................................39
Fuel Pressure Check .................................................39
Fuel Pressure Regulator Check ................................40
Injector .......................................................................41
How to Check Idle Speed and Ignition Timing ..........42
Idle Speed/Ignition Timing/Idle Mixture Ratio
Adjustment .................................................................43
Idle Air Volume Learning ...........................................57ON BOARD DIAGNOSTIC SYSTEM
DESCRIPTION...............................................................59
Introduction ................................................................59
Two Trip Detection Logic ...........................................59
Emission-related Diagnostic Information ...................60
Malfunction Indicator Lamp (MIL) ..............................74
OBD System Operation Chart ...................................75
CONSULT-II ...............................................................81
Generic Scan Tool (GST) ..........................................95
TROUBLE DIAGNOSIS - INTRODUCTION..................97
Introduction ................................................................97
Work Flow ..................................................................99
TROUBLE DIAGNOSIS - BASIC INSPECTION.........101
Basic Inspection.......................................................101
TROUBLE DIAGNOSIS - GENERAL
DESCRIPTION............................................................. 116
DTC Inspection Priority Chart.................................. 116
Fail-safe Chart ......................................................... 117
Symptom Matrix Chart ............................................. 118
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................122
Major Sensor Reference Graph in Data Monitor
Mode ........................................................................124
ECM Terminals and Reference Value .....................127
TROUBLE DIAGNOSIS - SPECIFICATION VALUE..136
Description ...............................................................136
Testing Condition .....................................................136
Inspection Procedure ...............................................136
Diagnostic Procedure ..............................................137
TROUBLE DIAGNOSIS FOR INTERMITTENT
INCIDENT.....................................................................140
Description ...............................................................140
Diagnostic Procedure ..............................................140
TROUBLE DIAGNOSIS FOR POWER SUPPLY........141
ECM Terminals and Reference Value .....................141
Main Power Supply and Ground Circuit ..................142
DTC P0100 MASS AIR FLOW SENSOR (MAFS)......150
Component Description ...........................................150
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX

Special Service ToolsNBEC0007The actual shapes of Kent-Moore tools may differ from those of special service tools illustrated here.
Tool number
(Kent-Moore No.)
Tool nameDescription
KV10117100
(J36471-A)
Front heated oxygen
sensor wrench
Rear heated oxygen
sensor wrench
NT379
Loosening or tightening front and rear heated oxy-
gen sensors with 22 mm (0.87 in) hexagon nut
(J44321)
Fuel pressure adapter
and gauge kit
SEF326Z
Checking fuel pressure with pressure gauge
Commercial Service ToolsNBEC0008
Tool name
(Kent-Moore No.)Description
Leak detector
(J41416)
NT703
Locating the EVAP leak
EVAP service port
adapter
(J41413-OBD)
NT704
Applying positive pressure through EVAP service
port
Fuel filler cap adapter
NT653
Checking fuel tank vacuum relief valve opening
pressure
PREPARATION
Special Service Tools
EC-18

HARNESS CONNECTOR (SLIDE-LOCKING TYPE)=NBEL0003S02IA new style slide-locking type connector is used on certain systems and components, especially those
related to OBD.
IThe slide-locking type connectors help prevent incomplete locking and accidental looseness or disconnec-
tion.
IThe slide-locking type connectors are disconnected by pushing or pulling the slider. Refer to the illustra-
tion below.
CAUTION:
IDo not pull the harness or wires when disconnecting the connector.
IBe careful not to damage the connector support bracket when disconnecting the connector.
[Example]
SEL769V
HARNESS CONNECTOR
Description (Cont'd)
EL-6

NEW TERMNEW ACRONYM /
ABBREVIATIONOLD TERM
Manifold differential pressure MDP ***
Manifold differential pressure sensor MDPS ***
Manifold surface temperature MST ***
Manifold surface temperature sensor MSTS ***
Manifold vacuum zone MVZ ***
Manifold vacuum zone sensor MVZS ***
Mass air flow sensor MAFS Air flow meter
Mixture control solenoid valve MC solenoid valve Air-fuel ratio control solenoid valve
Multiport fuel injection System MFI system Fuel injection control
Neutral position switch *** Neutral switch
Nonvolatile random access memory NVRAM ***
On board diagnostic system OBD system Self-diagnosis
Open loop OL Open loop
Oxidation catalyst OC Catalyst
Oxidation catalytic converter system OC system ***
Oxygen sensor O2S Exhaust gas sensor
Park position switch *** Park switch
Park/neutral position switch PNP switch Park/neutral switch
Periodic trap oxidizer system PTOX system ***
Positive crankcase ventilation PCV Positive crankcase ventilation
Positive crankcase ventilation valve PCV valve PCV valve
Powertrain control module PCM ***
Programmable read only memory PROM ***
Pulsed secondary air injection control
solenoid valvePAIRC solenoid valve AIV control solenoid valve
Pulsed secondary air injection system PAIR system Air induction valve (AIV) control
Pulsed secondary air injection valve PAIR valve Air induction valve
Random access memory RAM ***
Read only memory ROM ***
Scan tool ST ***
Secondary air injection pump AIR pump ***
Secondary air injection system AIR system ***
Sequential multiport fuel injection system SFI system Sequential fuel injection
Service reminder indicator SRI ***
Simultaneous multiport fuel injection sys-
tem*** Simultaneous fuel injection
Smoke puff limiter system SPL system ***
Supercharger SC ***
MA
EM
LC
EC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
SAE J1930 TERMINOLOGY LIST
SAE J1930 Terminology List (Cont'd)
GI-53

Brake fluid change ...........................................BR-7
Brake fluid level .............................................MA-25
Brake fluid level and line check .......................BR-7
Brake hydraulic line ..........................................BR-9
Brake inspection ............................................MA-25
Brake lines and cables inspection .................MA-25
Brake lining wear temporary checking ..........MA-26
Brake master cylinder ....................................BR-16
Brake pedal ....................................................BR-14
Bulb specifications ........................................EL-456
Bumper, front ..................................................BT-12
Bumper, rear ...................................................BT-15
BYPS/V - Wiring diagram ....................EC-587, 594
C
Camshaft inspection ......................................EM-42
Camshaft position sensor (PHASE) .............EC-342
Canister-See EVAP canister ..........................EC-32
Center bearing assembly (propeller
shaft) .............................................................PD-9
Center bearing disassembly (propeller
shaft) .............................................................PD-7
Center case (Transfer) ..................................TF-123
CHARGE - Wiring diagram ............................SC-20
Charging system ............................................SC-19
Chassis and body maintenance ....................MA-21
CHIME - Wiring diagram...............................EL-127
CIGAR - Wiring diagram ...............................EL-148
Cigarette lighter.............................................EL-148
Circuit breaker.................................................EL-16
CKPS - Wiring diagram ................................EC-334
Closed loop control (Left bank) ....................EC-491
Closed loop control (Right bank) .................EC-491
Closed throttle position switch .....................EC-431
Clutch drum (Transfer) ..................................TF-125
Clutch force release limit adjustment .............TF-39
Clutch pressure switch (Transfer) .................TF-111
Coil spring (front)..............................................SU-8
Coil spring (rear) ............................................SU-18
Collision diagnosis..........................................RS-59
Combination lamp, front, removal and
installation ...................................................BT-12
Combination lamp, rear, removal and
installation ...................................................BT-35
Combination meter..........................................EL-94
Combination meter removal and instal-
lation - See Instrument panel ......................BT-21
Combination switch .........................................EL-28
COMPAS - Wiring diagram ...........................EL-111
Compass .......................................................EL-110
Component Location (auto A/C).....................HA-27
Compression pressure ...................................EM-14
Compressor clutch removal and
installation .................................................HA-150
Compressor precaution ....................................HA-6
Compressor special service tool ....................HA-10
Connecting rod...............................................EM-65
Connecting rod bearing clearance.................EM-69
Connecting rod bushing clearance ................EM-70Connector inspection .......................................GI-21
Console box - See Instrument panel ..............BT-21
CONSULT for ABS .........................................BR-43
CONSULT for all-mode 4WD ..........................TF-30
CONSULT for engine .....................................EC-81
CONSULT-II general information .....................GI-38
Control valve (A/T) ........................................AT-301
Control valve (Transfer) ................................TF-128
Converter housing installation .......................AT-278
Coolant mixture ratio......................................MA-12
Coolant replacement ......................................MA-14
Cooling circuit (engine) ...................................LC-10
``Crankcase emission control system -
See positive crankcase ventilation''............EC-38
Crankshaft ......................................................EM-67
Crankshaft position sensor (POS) ...............EC-334
Crankshaft position sensor (POS)
chipping ....................................................EC-517
Crankshaft position sensor (REF) ................EC-510
Cruise control - See ASCD ...........................EL-221
Cylinder block ................................................EM-61
Cylinder head .................................................EM-38
Cylinder head bolt tightening .........................EM-49
D
Data link connector for Consult......................EC-81
Daytime light system.......................................EL-46
Daytime running light - See Daytime
light system .................................................EL-46
DEF - Wiring diagram ...................................EL-153
Detonation sensor - See Knock sensor .......EC-328
Diagnostic trouble code (DTC) for OBD
system ....................................................EC-8, 60
Diagnostic trouble code (DTC) inspec-
tion priority chart .......................................EC-116
Differential carrier assembly.....................PD-30, 57
Differential carrier disassembly ......................PD-44
Differential gear oil replacement ....................MA-24
Dimensions ......................................................GI-43
D/LOCK - Wiring diagram .............................EL-256
Dome light - See Interior lamp .......................EL-88
Door glass .......................................................BT-18
Door lock .........................................................BT-18
Door mirror ......................................................BT-56
Door trim .........................................................BT-30
Door, front .......................................................BT-18
Door, rear ........................................................BT-20
Drive belt inspection ......................................MA-13
Drive chain (Transfer) ...................................TF-125
Drive pinion diff. inspection ......................PD-23, 47
Drive pinion height ...................................PD-25, 53
Drive plate runout ..........................................EM-70
Drive shaft (front)............................................AX-10
Dropping resistor (A/T) ..................................AT-167
DTC work support ..........................................EC-93
DTRL - Wiring diagram ...................................EL-51
GI
MA
EM
LC
EC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
ALPHABETICAL INDEX
IDX-3