2004 INFINITI QX56 Engine Control System

BRC-42
[VDC/TCS/ABS]
TROUBLE DIAGNOSIS FOR SELF-DIAGNOSTIC ITEMS
Revision: August 20072004 QX56
tion. However, in this case there is no malfunction in yaw rate sensor system. Take vehicle off of turn
table or other moving surface, and start engine. Results will return to normal.
Is the above displayed in the self-diagnosis display items?
Yes >> GO TO 2.
No >> Inspection End.
2. CONNECTOR INSPECTION
Disconnect the ABS actuator and electric unit (control unit) connector E125 and yaw rate/side/decel G sensor
connector M108.
Check the terminals for deformation, disconnection, looseness or damage.
OK or NG
OK >> GO TO 3.
NG >> Repair or replace as necessary.
3. YAW RATE/SIDE/DECEL G SENSOR HARNESS INSPECTION
1. Turn off the ignition switch and disconnect yaw rate/side/decel G sensor connector M108 and ABS actua-
tor and electric unit (control unit) connector E125.
2. Check continuity between the ABS actuator and electric unit (control unit) connector E125 and the yaw
rate/side/decel G sensor connector M108.
OK or NG
OK >> GO TO 4.
NG >> Repair or replace as necessary.
4. YAW RATE/SIDE/DECEL G SENSOR INSPECTION
1. Connect the yaw rate/side/decel G sensor connector M108 and ABS actuator and electric unit (control
unit) connector E125.
2. Use “DATA MONITOR” to check if the yaw rate/side/decel G sensor signals are normal.
OK or NG
OK >> Inspection End.
NG >> Replace the yaw rate/side/decel G sensor. Refer to BRC-69, "
Removal and Installation" . ABS actuator and electric unit
(control unit) harness connector
E125Yaw rate/side/decel G sensor
harness connector M108 Continuity
6 (Y/R) 3 (Y/R) Yes
24 (P) 5 (P) Yes
25 (G/R) 1 (G/R) Yes
29 (G/W) 2 (G/W) Yes
Vehicle statusYaw rate sensor
(Data monitor standard)Side G sensor
(Data monitor standard)Decel G Sensor
(Data monitor standard)
When stopped -4 to +4 deg/s -1.1 to +1.1 m/s -0.11 G to +0.11 G
Right turn Negative value Negative value -
Left turn Positive value Positive value -
Speed up - - Negative value
Speed down - - Positive value

TROUBLE DIAGNOSES FOR SYMPTOMS
BRC-59
[VDC/TCS/ABS]
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Revision: August 20072004 QX56
Long Stopping DistanceEFS0044V
1. CHECK BASE BRAKING SYSTEM PERFORMANCE
1. Disable ABS by disconnecting ABS actuator and electric unit (control unit) connector.
2. Drive vehicle and check brake operation.
NOTE:
Stopping distance may be longer than vehicles without ABS when road condition is slippery.
OK or NG
OK >> Go to BRC-57, "ABS Works Frequently" .
NG >> Perform Basic Inspection. Refer to BRC-23, "
Basic Inspection" .
ABS Does Not WorkEFS0044W
CAUTION:
The ABS does not operate when the vehicle speed is 10 km/h (6 MPH) or less.
1. CHECK WARNING LAMP ACTIVATION
Turn ignition switch ON and check for warning lamp activation.

Warning lamp should activate for approximately 1 second after turning the ignition switch ON.
OK or NG
OK >> Carry out self-diagnosis. Refer to BRC-29, "SELF-DIAGNOSIS" .
NG >> Go to BRC-60, "
ABS Warning Lamp Does Not Come On When Ignition Switch Is Turned On" .
Pedal Vibration or ABS Operation NoiseEFS0044X
NOTE:
During ABS activation, pedal vibration may be felt and a noise may be heard. This is normal and does not indi-
cate a malfunction.
1. CHECK SYMPTOM
1. Apply brake.
2. Start engine.
Does the symptom occur only when engine is started?
YES >> Carry out self-diagnosis. Refer to BRC-29, "SELF-DIAGNOSIS" .
NO >> GO TO 2.
2. RECHECK SYMPTOM
Does the symptom occur only when electrical equipment switches (such as headlamps) are turned on?
YES >> Check for radio, antenna or related wiring that is routed too close to the ABS actuator and electric
unit (control unit) and reroute as necessary.
NO >> Go to BRC-57, "
ABS Works Frequently" .

TROUBLE DIAGNOSES FOR SYMPTOMS
BRC-61
[VDC/TCS/ABS]
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Revision: August 20072004 QX56
Vehicle Jerks During TCS/VDC ActivationEFS00450
1. ABS ACTUATOR AND ELECTRIC UNIT (CONTROL UNIT) SELF-DIAGNOSIS
Perform ABS actuator and electric unit (control unit) self-diagnosis.
Are self-diagnosis result items displayed?
YES >> After checking and repairing the applicable item, perform the ABS actuator and electric unit (con-
trol unit) self-diagnosis again.
NO >> GO TO 2.
2. ENGINE SPEED SIGNAL INSPECTION
Perform data monitor with CONSULT-II for the ABS actuator and electric unit (control unit).
Is the engine speed at idle 400 rpm or higher?
YES >> GO TO 4.
NO >> GO TO 3.
3. ECM SELF-DIAGNOSIS
Perform ECM self-diagnosis.
Are self-diagnosis result items displayed?
YES >> After checking and repairing the applicable item, perform the ECM self-diagnosis again.
NO >> GO TO 4.
4. TCM SELF-DIAGNOSIS
Perform TCM self-diagnosis.
Are self-diagnosis result items displayed?
YES >> After checking and repairing the applicable item, perform the TCM self-diagnosis again.
NO >> GO TO 5.
5. CONNECTOR INSPECTION
Disconnect the ABS actuator and electric unit (control unit) connector and the ECM connectors and check the
terminals for deformation, disconnection, looseness or damage.
OK or NG
OK >> GO TO 6.
NG >> Repair or replace as necessary.
6. CAN COMMUNICATION INSPECTION
Check the CAN communication system. Refer to BRC-54, "
CAN Communication System Inspection" .
OK or NG
OK >> Inspection End.
NG >> Refer to LAN-5, "
CAN COMMUNICATION" .

DI-1
DRIVER INFORMATION SYSTEM
K ELECTRICAL
CONTENTS
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SECTION DI
A
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DI
Revision: August 20072004 QX56 PRECAUTION ............................................................ 3
Precautions for Supplemental Restraint System
(SRS) “AIR BAG” and “SEAT BELT PRE-TEN-
SIONER” .................................................................. 3
Wiring Diagrams and Trouble Diagnosis .................. 3
PREPARATION ........................................................... 4
Commercial Service Tool ......................................... 4
COMBINATION METERS ........................................... 5
System Description .................................................. 5
UNIFIED METER CONTROL UNIT ...................... 5
POWER SUPPLY AND GROUND CIRCUIT ........ 6
WATER TEMPERATURE GAUGE ........................ 6
ENGINE OIL PRESSURE GAUGE ....................... 6
A/T OIL TEMPERATURE GAUGE ........................ 6
VOLTAGE GAUGE ................................................ 6
TACHOMETER ..................................................... 6
FUEL GAUGE ....................................................... 6
SPEEDOMETER ................................................... 6
CAN COMMUNICATION SYSTEM DESCRIP-
TION ...................................................................... 6
Component Parts and Harness Connector Location ..... 7
Combination Meter ................................................... 8
CHECK .................................................................. 8
Circuit Diagram ........................................................ 9
Wiring Diagram — METER — ................................ 10
Terminals and Reference Value for Combination
Meter ...................................................................... 12
Meter/Gauge Operation and Odo/Trip Meter ......... 13
SELF-DIAGNOSIS FUNCTION .......................... 13
HOW TO INITIATE COMBINATION METER
SELF- DIAGNOSIS MODE ................................. 13
COMBINATION METER SELF-DIAGNOSIS
MODE FUNCTIONS ........................................... 13
How to Proceed With Trouble Diagnosis ................ 17
Diagnosis Flow ....................................................... 17
Power Supply and Ground Circuit Inspection ........ 18
Symptom Chart ...................................................... 19
Vehicle Speed Signal Inspection ............................ 19
Engine Oil Pressure Signal Inspection ................... 19
Water Temperature Signal Inspection .................... 21Engine Speed Signal Inspection ............................. 21
Fuel Level Sensor Unit Inspection .......................... 22
FUEL LEVEL SENSOR UNIT ............................. 22
LOW-FUEL WARNING LAMP ............................. 22
Fuel Gauge Fluctuates, Indicates Wrong Value, or
Varies ...................................................................... 24
Fuel Gauge Does Not Move to Full-position ........... 24
Electrical Components Inspection .......................... 25
FUEL LEVEL SENSOR UNIT CHECK ................ 25
Removal and Installation of Combination Meter ..... 25
COMPASS AND THERMOMETER ........................... 26
System Description ................................................. 26
OUTSIDE TEMPERATURE DISPLAY ................. 26
DIRECTION DISPLAY ......................................... 26
Wiring Diagram — COMPAS — ............................. 27
Trouble Diagnoses ................................................. 28
PRELIMINARY CHECK FOR THERMOMETER ... 28
INSPECTION/COMPASS AND THERMOME-
TER ..................................................................... 28
Calibration Procedure for Compass ....................... 29
CORRECTION FUNCTIONS OF COMPASS ...... 29
INITIAL CORRECTION PROCEDURE FOR
COMPASS ........................................................... 30
WARNING LAMPS .................................................... 31
Schematic ............................................................... 31
Wiring Diagram — WARN — .................................. 32
Oil Pressure Warning Lamp Stays Off (Ignition
Switch ON) ............................................................. 38
Oil Pressure Warning Lamp Does Not Turn Off (Oil
Pressure Is Normal) ................................................ 40
A/T INDICATOR ........................................................ 41
Wiring Diagram — AT/IND — ................................. 41
A/T Indicator Does Not Illuminate ........................... 42
WARNING CHIME ..................................................... 43
Component Parts and Harness Connector Location ... 43
System Description ................................................. 44
FUNCTION .......................................................... 44
IGNITION KEY WARNING CHIME ..................... 44
LIGHT WARNING CHIME ................................... 44
SEAT BELT WARNING CHIME ........................... 44

DI-6
COMBINATION METERS
Revision: August 20072004 QX56
POWER SUPPLY AND GROUND CIRCUIT
Power is supplied at all times

through 10A fuse [No.19, located in the fuse block (J/B)]

to combination meter terminal 8.
With the ignition switch in the ON or START position, power is supplied

through 10A fuse [No.14, located in the fuse block (J/B)]

to combination meter terminal 24.
With the ignition switch in the ACC or ON position, power is supplied

through 10A fuse [No.4, located in the fuse block (J/B)]

to combination meter terminal 1.
Ground is supplied

to combination meter terminal 17

through body grounds M57, M61 and M79.
WATER TEMPERATURE GAUGE
The water temperature gauge indicates the engine coolant temperature.
ECM provides an engine coolant temperature signal to combination meter via CAN communication lines.
ENGINE OIL PRESSURE GAUGE
The engine oil pressure gauge indicates the engine oil pressure.
The engine oil pressure gauge is regulated by the unified meter control unit and input from the oil pressure
sensor.
A/T OIL TEMPERATURE GAUGE
The A/T oil temperature gauge indicates the A/T fluid temperature.
TCM (transmission control module) provides an A/T fluid temperature signal to combination meter via CAN
communication lines.
V O LTA G E G A U G E
The voltage gauge indicates the battery/charging system voltage.
The voltage gauge is regulated by the unified meter control unit.
TACHOMETER
The tachometer indicates engine speed in revolutions per minute (rpm).
ECM provides an engine speed signal to combination meter via CAN communication lines.
FUEL GAUGE
The fuel gauge indicates the approximate fuel level in the fuel tank.
The fuel gauge is regulated by the unified meter control unit and a variable resistor signal supplied

to combination meter terminal 15.

through fuel level sensor unit and fuel pump terminal 2

through fuel level sensor unit and fuel pump terminal 5

from combination meter terminal 16
SPEEDOMETER
ABS actuator and electric unit (control unit) provides a vehicle speed signal to the combination meter via CAN
communication lines.
CAN COMMUNICATION SYSTEM DESCRIPTION
Refer to LAN-5, "CAN COMMUNICATION" .

EC-1
ENGINE CONTROL SYSTEM
B ENGINE
CONTENTS
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SECTION EC
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EC
Revision: August 20072004 QX56 INDEX FOR DTC ........................................................ 8
Alphabetical Index .................................................... 8
DTC No. Index ....................................................... 12
PRECAUTIONS ........................................................ 16
Precautions for Supplemental Restraint System
(SRS) “AIR BAG” and “SEAT BELT PRE-TEN-
SIONER” ................................................................ 16
On Board Diagnostic (OBD) System of Engine and
A/T .......................................................................... 16
Precaution .............................................................. 16
Wiring Diagrams and Trouble Diagnosis ................ 19
PREPARATION ......................................................... 20
Special Service Tools ............................................. 20
Commercial Service Tools ...................................... 22
ENGINE CONTROL SYSTEM .................................. 23
System Diagram ..................................................... 23
Vacuum Hose Drawing ........................................... 24
System Chart ......................................................... 25
Multiport Fuel Injection (MFI) System .................... 26
Electronic Ignition (EI) System ............................... 28
Nissan Torque Demand (NTD) Control System ..... 29
Air Conditioning Cut Control ................................... 30
Fuel Cut Control (at No Load and High Engine
Speed) .................................................................... 30
CAN communication .............................................. 31
BASIC SERVICE PROCEDURE .............................. 32
Idle Speed and Ignition Timing Check .................... 32
Idle Speed/Ignition Timing/Idle Mixture Ratio
Adjustment ............................................................. 33
Accelerator Pedal Released Position Learning ...... 44
Throttle Valve Closed Position Learning ................ 44
Idle Air Volume Learning ........................................ 44
Fuel Pressure Check .............................................. 46
ON BOARD DIAGNOSTIC (OBD) SYSTEM ............ 49
Introduction ............................................................ 49
Two Trip Detection Logic ........................................ 49
Emission-related Diagnostic Information ................ 50
IVIS (Infiniti Vehicle Immobilizer System — NATS) ... 63
Malfunction Indicator Lamp (MIL) ........................... 63
OBD System Operation Chart ................................ 66TROUBLE DIAGNOSIS ............................................ 71
Trouble Diagnosis Introduction ............................... 71
DTC Inspection Priority Chart ................................. 76
Fail-safe Chart ........................................................ 77
Basic Inspection ..................................................... 79
Symptom Matrix Chart ............................................ 84
Engine Control Component Parts Location ............ 88
Circuit Diagram ....................................................... 94
ECM Harness Connector Terminal Layout ............. 96
ECM Terminals and Reference Value ..................... 96
CONSULT-II Function ...........................................103
Generic Scan Tool (GST) Function .......................116
CONSULT-II Reference Value in Data Monitor .....118
Major Sensor Reference Graph in Data Monitor
Mode .....................................................................121
TROUBLE DIAGNOSIS - SPECIFICATION VALUE .123
Description ............................................................123
Testing Condition ..................................................123
Inspection Procedure ............................................123
Diagnostic Procedure ...........................................124
TROUBLE DIAGNOSIS FOR INTERMITTENT INCI-
DENT .......................................................................127
Description ............................................................127
Diagnostic Procedure ...........................................127
POWER SUPPLY AND GROUND CIRCUIT ...........128
Wiring Diagram .....................................................128
Diagnostic Procedure ...........................................129
Ground Inspection ................................................133
DTC U1000, U1001 CAN COMMUNICATION LINE .135
Description ............................................................135
On Board Diagnosis Logic ....................................135
DTC Confirmation Procedure ...............................135
Wiring Diagram .....................................................136
Diagnostic Procedure ...........................................137
DTC P0037, P0038, P0057, P0058 HO2S2 HEATER .138
Description ............................................................138
CONSULT-II Reference Value in Data Monitor Mode
.138
On Board Diagnosis Logic ....................................138
DTC Confirmation Procedure ...............................139

EC-7
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ECA
Revision: August 20072004 QX56 Component Inspection ......................................... 582
Removal and Installation ...................................... 582
IGNITION SIGNAL .................................................. 583
Component Description ........................................ 583
Wiring Diagram .................................................... 584
Diagnostic Procedure ........................................... 589
Component Inspection ......................................... 593
Removal and Installation ...................................... 594
INJECTOR CIRCUIT ............................................... 595
Component Description ........................................ 595
CONSULT-II Reference Value in Data Monitor Mode
. 595
Wiring Diagram .................................................... 596
Diagnostic Procedure ........................................... 597
Component Inspection ......................................... 600
Removal and Installation ...................................... 600
FUEL PUMP CIRCUIT ............................................ 601
Description ........................................................... 601
CONSULT-II Reference Value in Data Monitor Mode
. 601
Wiring Diagram .................................................... 602
Diagnostic Procedure ........................................... 603
Component Inspection ......................................... 606
Removal and Installation ...................................... 606
REFRIGERANT PRESSURE SENSOR ................. 607
Component Description ........................................ 607
Wiring Diagram .................................................... 608
Diagnostic Procedure ........................................... 609
Removal and Installation ....................................... 611
ELECTRICAL LOAD SIGNAL ................................ 612
Description ........................................................... 612
CONSULT-II Reference Value in Data Monitor Mode
. 612
Diagnostic Procedure ........................................... 612
ICC BRAKE SWITCH ............................................. 613
Component Description ........................................ 613
CONSULT-II Reference Value in Data Monitor Mode
. 613
Wiring Diagram .................................................... 614
Diagnostic Procedure ........................................... 615
Component Inspection ......................................... 619
ASCD BRAKE SWITCH ......................................... 621
Component Description ........................................ 621CONSULT-II Reference Value in Data Monitor Mode
.621
Wiring Diagram .....................................................622
Diagnostic Procedure ...........................................623
Component Inspection ..........................................627
ASCD INDICATOR ..................................................628
Component Description ........................................628
CONSULT-II Reference Value in Data Monitor Mode
.628
Wiring Diagram .....................................................629
Diagnostic Procedure ...........................................630
MIL AND DATA LINK CONNECTOR ......................631
Wiring Diagram .....................................................631
EVAPORATIVE EMISSION SYSTEM .....................633
Description ............................................................633
Component Inspection ..........................................636
Removal and Installation ......................................637
How to Detect Fuel Vapor Leakage ......................637
ON BOARD REFUELING VAPOR RECOVERY
(ORVR) ....................................................................640
System Description ...............................................640
Diagnostic Procedure ...........................................641
Component Inspection ..........................................643
POSITIVE CRANKCASE VENTILATION ...............645
Description ............................................................645
Component Inspection ..........................................645
AUTOMATIC SPEED CONTROL DEVICE (ASCD) .647
System Description ...............................................647
Component Description ........................................648
SERVICE DATA AND SPECIFICATIONS (SDS) ....649
Fuel Pressure .......................................................649
Idle Speed and Ignition Timing .............................649
Calculated Load Value ..........................................649
Mass Air Flow Sensor ...........................................649
Intake Air Temperature Sensor .............................649
Engine Coolant Temperature Sensor ...................649
A/F Sensor 1 Heater .............................................649
Heated Oxygen sensor 2 Heater ..........................649
Crankshaft Position Sensor (POS) .......................649
Camshaft Position Sensor (PHASE) ....................649
Throttle Control Motor ...........................................649
Injector ..................................................................650
Fuel Pump ............................................................650

EC-16Revision: August 2007
PRECAUTIONS
2004 QX56
PRECAUTIONSPFP:00001
Precautions for Supplemental Restraint System (SRS) “AIR BAG” and “SEAT
BELT PRE-TENSIONER”
UBS00GZ5
The Supplemental Restraint System such as “AIR BAG” and “SEAT BELT PRE-TENSIONER”, used along
with a front seat belt, helps to reduce the risk or severity of injury to the driver and front passenger for certain
types of collision. This system includes seat belt switch inputs and dual stage front air bag modules. The SRS
system uses the seat belt switches to determine the front air bag deployment, and may only deploy one front
air bag, depending on the severity of a collision and whether the front occupants are belted or unbelted.
Information necessary to service the system safely is included in the SRS and SB section of this Service Man-
ual.
WAR NIN G:

To 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 per-
formed by an authorized NISSAN/INFINITI dealer.

Improper 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 SRS section.

Do not use electrical test equipment on any circuit related to the SRS unless instructed to in this
Service Manual. SRS wiring harnesses can be identified by yellow and/or orange harnesses or
harness connectors.
On Board Diagnostic (OBD) System of Engine and A/TUBS00GZ6
The 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:

Be sure to turn the ignition switch OFF and disconnect the negative battery cable before any
repair or inspection work. The open/short circuit of related switches, sensors, solenoid valves,
etc. will cause the MIL to light up.

Be 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.)

Certain 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 PG-68, "
HAR-
NESS CONNECTOR" .

Be 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.

Be 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 EVAP system or fuel injection system,
etc.

Be sure to erase the unnecessary malfunction information (repairs completed) from the ECM and
TCM (Transmission control module) before returning the vehicle to the customer.
PrecautionUBS00GZ7

Always use a 12 volt battery as power source.

Do not attempt to disconnect battery cables while engine is
running.

Before connecting or disconnecting the ECM harness con-
nector, turn ignition switch OFF and disconnect negative
battery cable. Failure to do so may damage the ECM
because battery voltage is applied to ECM even if ignition
switch is turned OFF.

Before removing parts, turn ignition switch OFF and then
disconnect battery ground cable.
SEF 2 89 H