2004 INFINITI QX56 heater

ATC-176
REFRIGERANT LINES
Revision: August 20072004 QX56
2. Remove the defroster mode door arm.
3. Separate the heater core and cooling unit case.
4. Remove the evaporator.
INSTALLATION
Installation is in the reverse order of removal.
CAUTION:
Replace the O-rings on the low-pressure flexible hose and the high-pressure pipe with new ones.
Apply compressor oil to the O-rings before installing them.
Removal and Installation for Rear EvaporatorEJS002DS
Rear Heater and Cooling Unit Assembly
LJIA0135E
1. Front cover 2. Evaporator and heater core case 3. Evaporator
4. Side cover 5. Heater core 6. Rear blower motor
7. Blower motor case 8. Rear blower motor resistor

REFRIGERANT LINES
ATC-177
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Revision: August 20072004 QX56
REMOVAL
1. Remove the rear heater and cooling unit assembly from the vehicle. Refer to ATC-146, "REAR HEATER
AND COOLING UNIT ASSEMBLY" .
2. Remove the rear blower motor.
3. Remove the rear blower speed resistor.
4. Remove the rear air mix door motor.
5. Remove the rear duct and blend door assembly. Refer to AT C -
160, "DEFROSTER NOZZLE" .
6. Disassemble the rear heater and cooling unit assembly to
remove the evaporator.
INSTALLATION
Installation is in the reverse order of removal.
CAUTION:

Replace the O-rings on the rear A/C pipes with new ones. Apply compressor oil to the O-rings
before installing them.

After charging refrigerant, check for leaks.
Removal and Installation for Front Expansion ValveEJS002DT
REMOVAL
1. Discharge the refrigerant. Refer to ATC-162, "HFC-134a (R-134a) Service Procedure" .
2. Remove the front heater and cooling unit assembly. Refer to ATC-145, "
FRONT HEATER AND COOLING
UNIT ASSEMBLY" .
3. Remove the cooler grommet.
4. Remove the expansion valve.
INSTALLATION
Installation is in the reverse order of removal.
CAUTION:

Replace the O-rings on the A/C refrigerant pipes with new ones, then apply compressor oil to them
when installing them.

After charging refrigerant, check for leaks.
Removal and Installation for Rear Expansion ValveEJS002DU
REMOVAL
1. Discharge the refrigerant. Refer to ATC-162, "HFC-134a (R-134a) Service Procedure" .
2. Remove the rear RH interior side trim panel. Refer to EI-34, "
Removal and Installation" .
3. Disconnect the A/C refrigerant pipes from the expansion valve.
LJIA0021E
WJIA0582E
Expansion valve bolts : 4 N·m (0.41 kg-m, 35 in-lb)
A/C refrigerant pipe to expansion valve bolt : Refer to ATC-164, "
Compo-
nents" .

ATC-180
REFRIGERANT LINES
Revision: August 20072004 QX56
2. When checking for leaks, circle each fitting completely with the
probe as shown.
3. Move the probe along each component at a speed of approxi-
mately 25 - 50 mm (1 - 2 in)/second as shown.
CHECKING PROCEDURE
NOTE:
To prevent inaccurate or false readings, make sure there is no refrigerant vapor, shop chemicals, or cigarette
smoke in the vicinity of the vehicle. Perform the leak test in a calm area (low air/wind movement) so that the
leaking refrigerant is not dispersed.
1. Turn the engine OFF.
2. Connect the manifold gauge set (J-39183-C) to the A/C service ports. Refer to ATC-162, "
SETTING OF
SERVICE TOOLS AND EQUIPMENT" .
3. Check if the A/C refrigerant pressure is at least 345 kPa (3.52 kg/cm
2 , 50 psi) above a temperature of
16°C (61°F). If less than specification, recover/evacuate and recharge the system with the specified
amount of refrigerant. Refer to ATC-162, "
HFC-134a (R-134a) Service Procedure" .
NOTE:
At temperatures below 16°C (61°F), leaks may not be detected since the system may not reach 345 kPa
(3.52 kg/cm
2 , 50 psi) pressure.
4. Perform the leak test from the high-pressure side (front A/C compressor discharge “a” to evaporator inlet
“f”, or rear piping connection “l”) to the low-pressure side (front A/C evaporator drain hose “g” to shaft seal
“k”, and rear A/C evaporator drain hose “o” to piping connection “r”). Refer to ATC-164, "
Components" .
Clean the component to be checked and carefully move the electronic refrigerant leak detector probe
completely around the following connections and components.

Compressor

Check the high and low-pressure pipe and hose fittings, relief valve, and compressor shaft seal

Check the liquid tank

Check the refrigerant pressure sensor

Check all around the service valves. Check that the service valve caps are tightly screwed on to the
service valves (to prevent leaks).
NOTE:
After removing manifold gauge set (J-39183-C) from the service valves, wipe any residue from the ser-
vice valves to prevent any false readings by the electronic refrigerant leak detector (J-41995).

Evaporator
With engine OFF, turn blower fan on “High” for at least 15 seconds to dissipate any refrigerant trace in
the heater and cooling unit assembly. Wait a minimum of 10 minutes accumulation time (refer to the
manufacturer's recommended procedure for actual wait time) before inserting the electronic refrigerant
leak detector probe into the heater and cooling unit assembly drain hose.
SHA7 06 E
SHA708EA

REFRIGERANT LINES
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Revision: August 20072004 QX56
NOTE:
Keep the probe inserted for at least 10 seconds. Use caution not to contaminate the probe tip with
water or dirt that may be in the drain hose.
5. If a leak is detected, verify at least once by blowing compressed air into the area of the suspected leak,
then repeat the leak check.
6. Do not stop when one leak is found. Continue to check for additional leaks at all system components and
connections.
7. If no leaks are found, perform steps 8 - 11.
8. Start the engine.
9. Set the heater A/C controls as follows:
NOTE:
For the automatic system, turn OFF the automatic controls and set the heater A/C controls manually.
a. A/C switch to ON
b. Air flow to VENT mode
c. Intake position to RECIRCULATION mode
d. Temperature to MAX cold
e. Fan speed to HIGH
10. Run the engine at 1,500 rpm for at least 2 minutes.
11. Turn the engine OFF and perform the leak check again following
steps 4 through 6 above.
Refrigerant leaks should be checked immediately after turning
the engine OFF. Begin with the leak detector at the compressor.
The pressure on the high pressure side will gradually drop after
the refrigerant circulation stops and pressure on the low pres-
sure side will gradually rise, as shown in the graph. Some leaks
are more easily detected when the pressure is high.
12. Before connecting the recovery/recycling equipment to the vehicle, check the recovery/recycling equip-
ment gauges. No refrigerant pressure should be displayed. If pressure is displayed, recover the refriger-
ant from the equipment lines and then check the refrigerant purity.
13. Confirm refrigerant purity in supply tank using recovery/recycling equipment and refrigerant identifier
equipment (J-41810-NI).
14. Confirm the refrigerant purity in the vehicle's A/C system using recovery/recycling equipment and refriger-
ant identifier equipment (J-41810-NI).
15. Discharge the A/C system using recovery/recycling equipment. Repair the leaking fitting or component as
necessary.
16. Evacuate and recharge the A/C system and perform the leak test to confirm that there are no refrigerant
leaks.
17. Conduct the Operational Check to ensure system works properly. Refer to ATC-56, "
Operational Check
(Front)" .
SHA8 39 E

AV-30
AUDIO
Revision: August 20072004 QX56
FOR CD ONLY
Noise InspectionEKS007KK
The vehicle itself can be a source of noise if noise prevention parts or electrical equipment is malfunctioning.
Check if noise is caused and/or changed by engine speed, ignition switch turned to each position, and opera-
tion of each piece of electrical equipment, and determine the cause.
NOTE:
The source of the noise can be found easily by listening to the noise while removing the fuses of electrical
components, one by one.
TYPE OF NOISE AND POSSIBLE CAUSE
Power Supply Circuit InspectionEKS007KL
1. CHECK FUSES

Check that the following fuses are not blown.
OK or NG
OK >> GO TO 2.
NG >> If fuse is blown, be sure to eliminate cause of problem before installing new fuse. Refer to PG-4,
"POWER SUPPLY ROUTING CIRCUIT" .
Symptom Possible cause
CD cannot be inserted.

CD

Audio unit CD cannot be ejected.
The CD cannot be played.
The sound skips, stops suddenly, or is distorted.
Occurrence condition Possible cause
Occurs only when engine is ON.A continuous growling noise occurs. The speed of
the noise varies with changes in the engine speed.

Ignition components
A whistling noise occurs while the engine speed is
high. A booming noise occurs while the engine is
running and the lighting switch is ON.

Generator
The occurrence of the noise is linked with the operation of the fuel pump.

Fuel pump condenser
Noise only occurs when various
electrical components are oper-
ating.A cracking or snapping sound occurs with the
operation of various switches.

Relay malfunction, audio unit malfunction
The noise occurs when various motors are operat-
ing.

Motor case ground

Motor
The noise occurs constantly, not just under certain conditions.

Rear defogger coil malfunction

Open circuit in printed heater

Poor ground of antenna amplifier or
antenna feeder line
A cracking or snapping sound occurs while the vehicle is being driven, especially
when it is vibrating excessively.

Ground wire of body parts

Ground due to improper part installation

Wiring connections or a short circuit
Unit Terminals Signal name Fuse No.
Audio unit6 Battery power 31
10 Ignition switch ACC or ON 4
AV s w i t c h1 Battery power 31
2 Ignition switch ACC or ON 4
BOSE speaker amp. 1 Battery power 31
Subwoofer 6 Battery power 17

THERMOSTAT AND WATER PIPING
CO-17
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Revision: August 20072004 QX56
THERMOSTAT AND WATER PIPINGPFP:21200
Removal and InstallationEBS00I54
REMOVAL
Removal of Thermostat
1. Drain engine coolant from the radiator. Refer to MA-12, "DRAINING ENGINE COOLANT" .
CAUTION:
Perform when engine is cold.
2. Remove air duct and resonator assembly. Refer to EM-14, "
REMOVAL" .
3. Remove engine room cover using power tools.
4. Disconnect water suction hose from water inlet.
5. Remove water inlet and thermostat.
Removal of Thermostat Housing, Water Outlet and Heater Pipe
1. Remove intake manifold. Refer to EM-15, "REMOVAL" .
2. Remove thermostat housing, water outlet and heater pipe.
Removal of Water Cut Valve
1. Drain engine coolant from the radiator. Refer to MA-12, "DRAINING ENGINE COOLANT" .
KBIA2501E
1. Heater pipe 2. Gasket 3. Water outlet
4. Gasket 5. O-ring 6. O-ring
7. Thermostat housing 8. Rubber ring 9. Thermostat
10. Water inlet 11. Water suction hose 12. Water suction pipe
13. Gasket 14. Heater pipe

CO-18Revision: August 2007
THERMOSTAT AND WATER PIPING
2004 QX56
CAUTION:
Perform when the engine is cold.
2. Remove air duct and resonator assembly. Refer to EM-14, "
REMOVAL" .
3. Remove engine room cover using power tools.
4. Disconnect heater hose (heater core side).
5. Remove heater hose bracket.
6. Disconnect the water cut valve connector.
7. Remove the water cut valve
INSPECTION AFTER REMOVAL

Place a thread so that it is caught in the valve of the thermostat.
Immerse fully in a container filled with water. Heat while stirring.

The valve opening temperature is the temperature at which the
valve opens and falls from the thread.

Continue heating. Check the full-open lift amount.

After checking the full-open lift amount, lower the water temper-
ature and check the valve closing temperature.
Standard values:
INSTALLATION
Installation is in the reverse order of removal.
Installation of Thermostat

Install the thermostat with the whole circumference of each
flange part fit securely inside the rubber ring as shown.

Install the thermostat with the jiggle valve facing upwards.
Installation of Water Outlet Pipe and Heater Pipe
First apply a neutral detergent to the O-rings, then quickly insert the insertion parts of the water outlet pipe and
heater pipe into the installation holes.
INSPECTION AFTER INSTALLATION

Check for leaks of the engine coolant. Refer to CO-8, "CHECKING COOLING SYSTEM FOR LEAKS" .

Start and warm up the engine. Visually make sure that there is no leaks of the engine coolant.
SL C2 52 B
Thermostat
Valve opening temperature 80 - 84°C (176 - 183° F)
Full-open lift amount More than 10 mm/ 95°C (0.39 in/ 203°F)
Valve closing temperature 77°C (171°F) or higher
KBIA2502E

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