2001 INFINITI QX4 fuel pressure

SAT007J
ILine pressure is increased to a maximum irrespective of the
throttle opening when fluid temperature drops to þ10ÉC (14ÉF).
This pressure rise is adopted to prevent a delay in clutch and
brake operation due to extreme drop of fluid viscosity at low
temperature.
SHIFT CONTROLNBAT0180S02The shift is regulated entirely by electronic control to accommodate
vehicle speed and varying engine operations. This is accomplished
by electrical signals transmitted by the revolution sensor and
throttle position sensor. This results in improved acceleration per-
formance and fuel economy.
SAT008J
Control of Shift Solenoid Valves A and BNBAT0180S0201The TCM activates shift solenoid valves A and B according to sig-
nals from the throttle position sensor and revolution sensor to
select the optimum gear position on the basis of the shift schedule
memorized in the TCM.
The shift solenoid valve performs simple ON-OFF operation. When
set to ªONº, the drain circuit closes and pilot pressure is applied to
the shift valve.
[Relation between shift solenoid valves A and B and gear positions]
Shift solenoid valveGear position
D
1,21,11D2,22,12D3D4(OD) N-P
A ON (Closed) OFF (Open) OFF (Open) ON (Closed) ON (Closed)
B ON (Closed) ON (Closed) OFF (Open) OFF (Open) ON (Closed)
Control of Shift Valves A and BNBAT0180S0202
SAT047J
OVERALL SYSTEM
Control Mechanism (Cont'd)
AT-28

InspectionNBBR0014CAUTION:
ICarefully monitor brake fluid level at master cylinder.
IUse new brake fluid ªDOT 3º.
IBe careful not to splash brake fluid on painted areas; it
may cause paint damage. If brake fluid is splashed on
paint areas, wash it away with water immediately.
IDepress pedal slowly when raising front brake pressure.
ICheck rear brake pressure 2 seconds after front brake
pressure reaches specified value.
IDisconnect harness connectors from ABS actuator and
electric unit before checking.
SBR212E
1. Park vehicle on a level surface with vehicle unloaded*.
* Fuel, radiator coolant and engine oil full. Spare tire, jack,
hand tools and mats in designated positions.
2. Press a lever to the stopper bolt, then check length ªBº as fol-
lows:
Length ªBº Reference (Length ªLº)
207.7 mm (8.18 in) 217.3 mm (8.56 in)
3. If length ªBº is not within specification, adjust sensor spring
length.
Removal and InstallationNBBR0015CAUTION:
IRefill with new brake fluid ªDOT 3º.
IBe careful not to splash brake fluid on painted areas; it
may cause paint damage. If brake fluid is splashed on
painted areas, wash it away with water immediately.
IDo not reuse Load Sensing Valve once it is disassembled.
IReplace damaged Load Sensing Valve as an assembly.
IWhen disassembling, apply multi-purpose grease to all
rubbing areas.
LOAD SENSING VALVE (4WD)
Inspection
BR-12

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

DTC P0217 COOLANT OVERTEMPERATURE
ENRICHMENT PROTECTION.....................................314
On Board Diagnosis Logic.......................................314
Possible Cause ........................................................314
Overall Function Check ...........................................314
Diagnostic Procedure ..............................................316
Main 12 Causes of Overheating..............................319
DTC P0300 - P0306 NO.6-1CYLINDER
MISFIRE, MULTIPLE CYLINDER MISFIRE...............320
On Board Diagnosis Logic.......................................320
Possible Cause ........................................................320
DTC Confirmation Procedure ..................................321
Diagnostic Procedure ..............................................321
DTC P0325 KNOCK SENSOR (KS)...........................328
Component Description ...........................................328
ECM Terminals and Reference Value .....................328
On Board Diagnosis Logic.......................................328
Possible Cause ........................................................328
DTC Confirmation Procedure ..................................328
Wiring Diagram ........................................................330
Diagnostic Procedure ..............................................331
DTC P0335 CRANKSHAFT POSITION SENSOR
(CKPS) (POS)..............................................................334
Component Description ...........................................334
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................334
ECM Terminals and Reference Value .....................335
On Board Diagnosis Logic.......................................335
Possible Cause ........................................................335
DTC Confirmation Procedure ..................................336
Wiring Diagram ........................................................337
Diagnostic Procedure ..............................................338
DTC P0340 CAMSHAFT POSITION SENSOR
(CMPS) (PHASE).........................................................342
Component Description ...........................................342
ECM Terminals and Reference Value .....................342
On Board Diagnosis Logic.......................................342
Possible Cause ........................................................343
DTC Confirmation Procedure ..................................343
Wiring Diagram ........................................................344
Diagnostic Procedure ..............................................345
DTC P0420 (RIGHT BANK, -B1), P0430 (LEFT
BANK, -B2) THREE WAY CATALYST FUNCTION...347
On Board Diagnosis Logic.......................................347
Possible Cause ........................................................347
DTC Confirmation Procedure ..................................348
Overall Function Check ...........................................348
Diagnostic Procedure ..............................................349
DTC P0440 EVAP CONTROL SYSTEM (SMALL
LEAK) (NEGATIVE PRESSURE)................................352
On Board Diagnosis Logic.......................................352
Possible Cause ........................................................352DTC Confirmation Procedure ..................................354
Diagnostic Procedure ..............................................355
DTC P0443 EVAP CANISTER PURGE VOLUME
CONTROL SOLENOID VALVE (CIRCUIT).................367
Description ...............................................................367
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................367
ECM Terminals and Reference Value .....................368
On Board Diagnosis Logic.......................................368
Possible Cause ........................................................368
DTC Confirmation Procedure ..................................369
Wiring Diagram ........................................................370
Diagnostic Procedure ..............................................371
DTC P0446 EVAPORATIVE EMISSION (EVAP)
CANISTER VENT CONTROL VALVE (CIRCUIT)......374
Component Description ...........................................374
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................374
ECM Terminals and Reference Value .....................374
On Board Diagnosis Logic.......................................374
Possible Cause ........................................................375
DTC Confirmation Procedure ..................................375
Wiring Diagram ........................................................376
Diagnostic Procedure ..............................................377
DTC P0450 EVAPORATIVE EMISSION (EVAP)
CONTROL SYSTEM PRESSURE SENSOR..............381
Component Description ...........................................381
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................381
ECM Terminals and Reference Value .....................381
On Board Diagnosis Logic.......................................382
Possible Cause ........................................................382
DTC Confirmation Procedure ..................................382
Wiring Diagram ........................................................384
Diagnostic Procedure ..............................................385
DTC P0455 EVAP CONTROL SYSTEM (GROSS
LEAK)...........................................................................394
On Board Diagnosis Logic.......................................394
Possible Cause ........................................................394
DTC Confirmation Procedure ..................................396
Diagnostic Procedure ..............................................397
DTC P0460 FUEL LEVEL SENSOR FUNCTION
(SLOSH).......................................................................407
Component Description ...........................................407
On Board Diagnostic Logic......................................407
Possible Cause ........................................................407
DTC Confirmation Procedure ..................................407
Wiring Diagram ........................................................408
Diagnostic Procedure ..............................................409
DTC P0461 FUEL LEVEL SENSOR FUNCTION....... 411
Component Description ........................................... 411
On Board Diagnostic Logic...................................... 411
CONTENTS(Cont'd)
EC-4

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
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
CONTENTS(Cont'd)
EC-7

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

System ChartNBEC0013
Input (Sensor) ECM Function Output (Actuator)
ICamshaft position sensor (PHASE)
ICrankshaft position sensor (REF)
IMass air flow sensor
IEngine coolant temperature sensor
IHeated oxygen sensor 1 (front)
IIgnition switch
IThrottle position sensor
IClosed throttle position switch*3
IPark/neutral position (PNP) switch
IAir conditioner switch
IKnock sensor
IIntake air temperature sensor
IAbsolute pressure sensor
IEVAP control system pressure sensor*1
IBattery voltage
IPower steering oil pressure switch
IVehicle speed sensor
IFuel tank temperature sensor*1
ICrankshaft position sensor (POS)
IHeated oxygen sensor 2 (rear)*2
ITCM (Transmission control module)
IRefrigerant pressure sensor
IElectrical load
IFuel level sensor*1Fuel injection & mixture ratio control Injectors
Electronic ignition system Power transistor
Idle air control system IACV-AAC valve
Fuel pump control Fuel pump relay
On board diagnostic system MIL (On the instrument panel)
Swirl control valve controlSwirl control valve control solenoid
valve
Power valve control VIAS control solenoid valve
Heated oxygen sensor 1 heater (front) con-
trolHeated oxygen sensor 1 heater
(front)
Heated oxygen sensor 2 heater (rear) controlHeated oxygen sensor 2 heater
(rear)
EVAP canister purge flow controlEVAP canister purge volume con-
trol solenoid valve
Air conditioning cut control Air conditioner relay
ON BOARD DIAGNOSIS for EVAP systemIEVAP canister vent control valve
IVacuum cut valve bypass valve
*1: These sensors are not used to control the engine system. They are used only for the on board diagnosis.
*2: This sensor is not used to control the engine system under normal conditions.
*3: This switch will operate in place of the throttle position sensor to control EVAP parts if the sensor malfunctions.GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
ENGINE AND EMISSION CONTROL OVERALL SYSTEM
System Chart
EC-27

Multiport Fuel Injection (MFI) System
DESCRIPTIONNBEC0014Input/Output Signal ChartNBEC0014S01
Sensor Input Signal to ECMECM func-
tionActuator
Crankshaft position sensor (POS) Engine speed (POS signal)
Fuel injec-
tion & mix-
ture ratio
controlInjectors Crankshaft position sensor (REF) Engine speed (REF signal)
Camshaft position sensor (PHASE) Piston position
Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Heated oxygen sensor 1 (front) Density of oxygen in exhaust gas
Throttle position sensorThrottle position
Throttle valve idle position
Park/neutral position (PNP) switch Gear position
Vehicle speed sensor Vehicle speed
Ignition switch Start signal
Air conditioner switch Air conditioner operation
Knock sensor Engine knocking condition
Battery Battery voltage
Absolute pressure sensor Ambient air barometric pressure
Power steering oil pressure switch Power steering operation
Heated oxygen sensor 2 (rear)* Density of oxygen in exhaust gas
*: Under normal conditions, this sensor is not for engine control operation.
Basic Multiport Fuel Injection SystemNBEC0014S02The amount of fuel injected from the fuel injector is determined by the ECM. The ECM controls the length of
time the valve remains open (injection pulse duration). The amount of fuel injected is a program value in the
ECM memory. The program value is preset by engine operating conditions. These conditions are determined
by input signals (for engine speed and intake air) from both the crankshaft position sensor and the mass air
flow sensor.
Various Fuel Injection Increase/Decrease CompensationNBEC0014S03In addition, the amount of fuel injected is compensated to improve engine performance under various oper-
ating conditions as listed below.

IDuring warm-up
IWhen starting the engine
IDuring acceleration
IHot-engine operation
IWhen selector lever is changed from ªNº to ªDº
IHigh-load, high-speed operation

IDuring deceleration
IDuring high engine speed operation
ENGINE AND EMISSION BASIC CONTROL SYSTEM DESCRIPTION
Multiport Fuel Injection (MFI) System
EC-28