2004 INFINITI QX56 torque

EC-1
ENGINE CONTROL SYSTEM
B ENGINE
CONTENTS
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SECTION EC
A
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

PRECAUTIONS
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Revision: August 20072004 QX56

Do not operate fuel pump when there is no fuel in lines.

Tighten fuel hose clamps to the specified torque.

Do not depress accelerator pedal when starting.

Immediately after starting, do not rev up engine unneces-
sarily.

Do not rev up engine just prior to shutdown.

When installing C.B. ham radio or a mobile phone, be sure
to observe the following as it may adversely affect elec-
tronic control systems depending on installation location.
–Keep the antenna as far as possible from the electronic
control units.
–Keep the antenna feeder line more than 20 cm (8 in) away
from the harness of electronic controls.
Do not let them run parallel for a long distance.
–Adjust the antenna and feeder line so that the standing-
wave radio can be kept smaller.
–Be sure to ground the radio to vehicle body.
Wiring Diagrams and Trouble DiagnosisUBS00GZ8
When you read wiring diagrams, refer to the following:

GI-15, "How to Read Wiring Diagrams"

PG-4, "POWER SUPPLY ROUTING CIRCUIT" for power distribution circuit
When you perform trouble diagnosis, refer to the following:

GI-11, "HOW TO FOLLOW TEST GROUPS IN TROUBLE DIAGNOSES"

GI-27, "How to Perform Efficient Diagnosis for an Electrical Incident"
BBIA0402E
SEF 7 09 Y
SEF 7 08 Y

ENGINE CONTROL SYSTEM
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Revision: August 20072004 QX56
System ChartUBS00GZD
*1: This sensor is not used to control the engine system. This is used only for the on board diagnosis.
*2: This sensor is not used to control the engine system under normal conditions.
*3: This input signal is sent to the ECM through CAN communication line.
*4: This output signal is sent from the ECM through CAN communication line.Input (Sensor) ECM Function Output (Actuator)

Camshaft position sensor (PHASE)

Crankshaft position sensor (POS)

Mass air flow sensor

Engine coolant temperature sensor

A/F sensor 1

Throttle position sensor

Accelerator pedal position sensor

Park/neutral position (PNP) switch

Intake air temperature sensor

Power steering pressure sensor

Ignition switch

Battery voltage

Knock sensor

Refrigerant pressure sensor

Stop lamp switch

ASCD steering switch

ASCD brake switch

Fuel level sensor*1 *3

EVAP control system pressure sensor

Fuel tank temperature sensor*1

Heated oxygen sensor 2*2

TCM (Transmission control module)*3

ABS actuator and electric unit (control unit)*3

Air conditioner switch*3

Wheel sensor*3

Electrical load signal*3
Fuel injection & mixture ratio control Fuel injector
Electronic ignition system Power transistor
Nissan torque demand control system

Electric throttle control actuator

Fuel injector
Fuel pump control Fuel pump relay
ASCD vehicle speed control Electric throttle control actuator
On board diagnostic system
MIL (On the instrument panel)*
4
A/F sensor 1 heater control A/F sensor 1 heater
Heated oxygen sensor 2 heater control Heated oxygen sensor 2 heater
EVAP canister purge flow controlEVAP canister purge volume control
solenoid valve
Air conditioning cut control
Air conditioner relay*
4
Cooling fan control
Cooling fan relay*4
ON BOARD DIAGNOSIS for EVAP system EVAP canister vent control valve

ENGINE CONTROL SYSTEM
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Revision: August 20072004 QX56

At idle

At low battery voltage

During acceleration
The knock sensor retard system is designed only for emergencies. The basic ignition timing is programmed
within the anti-knocking zone, if recommended fuel is used under dry conditions. The retard system does not
operate under normal driving conditions. If engine knocking occurs, the knock sensor monitors the condition.
The signal is transmitted to the ECM. The ECM retards the ignition timing to eliminate the knocking condition.
Nissan Torque Demand (NTD) Control SystemUBS00GZG
INPUT/OUTPUT SIGNAL CHART
*1: Signal is sent to the ECM through CAN communication line.
SYSTEM DESCRIPTION
NTD control system decides the target traction based on the accelerator operation status and the current driv-
ing condition. It then selects the engine torque target by correcting running resistance and atmospheric pres-
sure, and controlling the power-train. Using electric throttle control actuator, it achieves the engine torque
development target which corresponds linearly to the driver's accelerator operation.
Running resistance correction control compares the engine torque estimate value, measured vehicle acceler-
ation, and running resistance on a flat road, and estimates vehicle weight gain and running resistance varia-
tion caused by slopes to correct the engine torque estimate value.
Atmospheric pressure correction control compares the engine torque estimate value from the airflow rate and
the target engine torque for the target traction, and estimates variation of atmospheric pressure to correct the
target engine torque. This system achieves powerful driving without reducing engine performance in the prac-
tical speed range in mountains and high-altitude areas.
Sensor Input signal to ECM ECM function Actuator
Camshaft position sensor (PHASE)
Crankshaft position sensor (POS)Engine speed
NTD controlElectric throttle con-
trol actuator and fuel
injector Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Throttle position sensor Throttle position
Accelerator pedal position sensor Accelerator pedal position
Park/Neutral position (PNP) switch Gear position
Power steering pressure sensor Power steering operation
Battery Battery voltage
TCM (CAN communication) A/T control signal
Air conditioner switch*
1Air conditioner operation
ABS actuator and electric unit (control unit)*
1VDC/TCS/ABS operation
Wheel sensor*
1Vehicle speed
Electrical load*
1Electrical load signal

EC-450Revision: August 2007
DTC P1273, P1283 A/F SENSOR 1
2004 QX56
Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
Diagnostic ProcedureUBS00H9Y
1. CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.
Refer to EC-133, "
Ground Inspection" .
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
2. RETIGHTEN A/F SENSOR 1
Loosen and retighten the A/F sensor 1.
>> GO TO 3.
TER-
MINAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
57 L/P
A/F sensor 1 (Bank 2)[Engine is running]

Warm-up condition

Idle speedApproximately 2.6V
58 GR/GApproximately 2.3V
76 G/LApproximately 3.1V
77 BR/BApproximately 2.3V
BBIA0354E
Tightening torque: 50 N-m (5.1 kg-m, 37 ft-lb)
BBIA0375E

DTC P1274, P1284 A/F SENSOR 1
EC-459
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Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
Diagnostic ProcedureUBS00HA5
1. CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.
Refer to EC-133, "
Ground Inspection" .
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
2. RETIGHTEN A/F SENSOR 1
Loosen and retighten the A/F sensor 1.
>> GO TO 3.
TER-
MINAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
57 L/P
A/F sensor 1 (Bank 2)[Engine is running]

Warm-up condition

Idle speedApproximately 2.6V
58 GR/GApproximately 2.3V
76 G/LApproximately 3.1V
77 BR/BApproximately 2.3V
BBIA0354E
Tightening torque: 50 N-m (5.1 kg-m, 37 ft-lb)
BBIA0375E

EC-478Revision: August 2007
DTC P1278, P1288 A/F SENSOR 1
2004 QX56
Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
Diagnostic ProcedureUBS00HAK
1. CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.
Refer to EC-133, "
Ground Inspection" .
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
2. RETIGHTEN A/F SENSOR 1
Loosen and retighten the A/F sensor 1.
>> GO TO 3.
TER-
MINAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
57 L/P
A/F sensor 1 (Bank 2)[Engine is running]

Warm-up condition

Idle speedApproximately 2.6V
58 GR/GApproximately 2.3V
76 G/LApproximately 3.1V
77 BR/BApproximately 2.3V
BBIA0354E
Tightening torque: 50 N-m (5.1 kg-m, 37 ft-lb)
BBIA0375E

EC-490Revision: August 2007
DTC P1279, P1289 A/F SENSOR 1
2004 QX56
Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
Diagnostic ProcedureUBS00HAR
1. CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.
Refer to EC-133, "
Ground Inspection" .
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
2. RETIGHTEN A/F SENSOR 1
Loosen and retighten the A/F sensor 1.
>> GO TO 3.
TER-
MINAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
57 L/P
A/F sensor 1 (Bank 2)[Engine is running]

Warm-up condition

Idle speedApproximately 2.6V
58 GR/GApproximately 2.3V
76 G/LApproximately 3.1V
77 BR/BApproximately 2.3V
BBIA0354E
Tightening torque: 50 N-m (5.1 kg-m, 37 ft-lb)
BBIA0375E