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EC-18Revision: August 2007
PRECAUTIONS
2004 QX56
After performing each TROUBLE DIAGNOSIS, perform DTC
Confirmation Procedure or Overall Function Check.
The DTC should not be displayed in the DTC Confirmation
Procedure if the repair is completed. The Overall Function
Check should be a good result if the repair is completed.
When measuring ECM signals with a circuit tester, never
allow the two tester probes to contact.
Accidental contact of probes will cause a short circuit and
damage the ECM power transistor.
Do not use ECM ground terminals when measuring input/
output voltage. Doing so may result in damage to the ECM's
transistor. Use a ground other than ECM terminals, such as
the ground.
B1 indicates the bank 1, B2 indicates the bank 2 as shown
in the figure.
SEF 2 17 U
SEF 3 48 N
PBIB11 44 E
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PRECAUTIONS
EC-19
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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
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EC-20Revision: August 2007
PREPARATION
2004 QX56
PREPARATIONPFP:00002
Special Service ToolsUBS00GZ9
The actual shapes of Kent-Moore tools may differ from those of special service tools illustrated here.
Tool number
(Kent-Moore No.)
Tool nameDescription
EG17650301
(J-33984-A)
Radiator cap tester
adapterAdapting radiator cap tester to radiator cap and ra-
diator filler neck
a: 28 (1.10) dia.
b: 31.4 (1.236) dia.
c: 41.3 (1.626) dia.
Unit: mm (in)
KV10117100
(J-36471-A)
Heated oxygen sensor
wrenchLoosening or tightening heated oxygen sensors
with 22 mm (0.87 in) hexagon nut
KV10114400
(J-38365)
Heated oxygen sensor
wrenchLoosening or tightening heated oxygen sensors
a: 22 mm (0.87 in)
(J-44626)
Air fuel ratio (A/F) sen-
sor wrenchLoosening or tightening air fuel ratio (A/F) sensor 1
(J-44321)
Fuel pressure gauge
kitChecking fuel pressure
(J-44321-6)
Fuel pressure adapterConnecting fuel pressure gauge to quick connec-
tor type fuel lines.
(J-45488)
Quick connector re-
leaseRemove fuel tube quick connectors in engine
room.
S-NT564
S-NT379
S-NT636
LEM054
LEC642
LBIA0376E
PBIC0198E
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PREPARATION
EC-21
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KV109E0010
(J-46209)
Break-out boxMeasuring the ECM signals with a circuit tester
KV109E0080
(J-45819)
Y-cable adapterMeasuring the ECM signals with a circuit tester
(J-23688)
Engine coolant refrac-
tometerChecking concentration of ethylene glycol in en-
gine coolant Tool number
(Kent-Moore No.)
Tool nameDescription
S-NT825
S-NT826
W BIA0539E
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EC-22Revision: August 2007
PREPARATION
2004 QX56
Commercial Service ToolsUBS00GZA
Tool name
(Kent-Moore No.)Description
Leak detector
i.e.: (J-41416)Locating the EVAP leak
EVAP service port
adapter
i.e.: (J-41413-OBD)Applying positive pressure through EVAP service
port
Fuel filler cap adapter
i.e.: (MLR-8382)Checking fuel tank vacuum relief valve opening
pressure
Socket wrench Removing and installing engine coolant tempera-
ture sensor
Oxygen sensor thread
cleaner
i.e.: (J-43897-18)
(J-43897-12)Reconditioning the exhaust system threads before
installing a new oxygen sensor. Use with anti-
seize lubricant shown below.
a: 18 mm diameter with pitch 1.5 mm for Zirco-
nia Oxygen Sensor
b: 12 mm diameter with pitch 1.25 mm for Tita-
nia Oxygen Sensor
Anti-seize lubricant
i.e.: (Permatex
TM
133AR or equivalent
meeting MIL specifica-
tion MIL-A-907)Lubricating oxygen sensor thread cleaning tool
when reconditioning exhaust system threads.
S-NT703
S-NT704
S-NT815
S-NT705
AEM488
S-NT779
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ENGINE CONTROL SYSTEM
EC-23
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ENGINE CONTROL SYSTEMPFP:23710
System DiagramUBS00GZB
PBIB2051E
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EC-24Revision: August 2007
ENGINE CONTROL SYSTEM
2004 QX56
Vacuum Hose DrawingUBS00GZC
Refer to EC-23, "System Diagram" for Vacuum Control System.
PBIB2052E
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ENGINE CONTROL SYSTEM
EC-25
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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