2004 INFINITI QX56 Engine Control System

TRANSMISSION ASSEMBLY
AT-255
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Revision: August 20072004 QX56
TRANSMISSION ASSEMBLYPFP:31020
Removal and Installation (4x2)UCS002J E
COMPONENTS
REMOVAL
CAUTION:
When removing the A/T assembly from engine, first remove the crankshaft position sensor (POS) from
the A/T assembly.
Be careful not to damage sensor edge.
1. Disconnect the negative battery terminal.
2. Remove engine cover.
3. Remove A/T fluid indicator gauge.
4. Remove engine under cover with power tool.
5. Remove exhaust front tube and center muffler with power tool. Refer to EX-3, "
Removal and Installation" .
6. Remove rear propeller shaft. Refer to PR-9, "
REMOVAL" .
7. Remove A/T control cable. Refer to AT- 2 3 3 , "
SHIFT CONTROL SYSTEM" .
1. A/T fluid indicator pipe 2. A/T fluid indicator 3. O-ring
4. Transmission assembly 5. Fluid cooler tube 6. A/T cross member
7. Insulator 8. Copper washers
LCIA0333E

AT-258
TRANSMISSION ASSEMBLY
Revision: August 20072004 QX56
Removal and Installation (4x4) UCS002J F
COMPONENTS
REMOVAL
CAUTION:
When removing the A/T assembly from engine, first remove the crankshaft position sensor (POS) from
the A/T assembly.
Be careful not to damage sensor edge.
1. Disconnect the negative battery terminal.
2. Remove engine cover with power tool.
3. Remove A/T fluid indicator.
4. Remove engine under cover with power tool.
5. Remove exhaust front tube and center muffler with power tool. Refer to EX-3, "
Removal and Installation" .
6. Remove propeller shaft. Refer to PR-5, "
REMOVAL" (front), or PR-9, "REMOVAL" (rear).
7. Remove A/T control cable. Refer to AT-233, "
SHIFT CONTROL SYSTEM" .
1. A/T fluid indicator pipe 2. A/T fluid indicator 3. O-ring
4. Transmission assembly 5. Fluid cooler tube 6. Copper washer
7. A/T cross member 8. Insulator
WCIA0257E

ATC-2Revision: August 20072004 QX56 TROUBLE DIAGNOSIS ............................................ 33
CONSULT-II Function (BCM) .................................. 33
CONSULT-II BASIC OPERATION ....................... 33
DATA MONITOR .................................................. 34
How to Perform Trouble Diagnosis for Quick and
Accurate Repair ...................................................... 35
WORK FLOW ...................................................... 35
SYMPTOM TABLE .............................................. 35
Component Parts and Harness Connector Location ... 37
ENGINE COMPARTMENT .................................. 37
FRONT PASSENGER COMPARTMENT ............ 38
REAR PASSENGER COMPARTMENT ............... 39
Schematic ............................................................... 40
Wiring Diagram — A/C,A — ................................... 41
Front Air Control Terminals and Reference Value ... 51
PIN CONNECTOR TERMINAL LAYOUT ............ 51
TERMINALS AND REFERENCE VALUE FOR
FRONT AIR CONTROL ....................................... 51
A/C System Self-diagnosis Function ...................... 53
DESCRIPTION .................................................... 53
Operational Check (Front) ...................................... 56
CHECKING MEMORY FUNCTION ..................... 56
CHECKING BLOWER ......................................... 56
CHECKING DISCHARGE AIR ............................ 57
CHECKING RECIRCULATION ............................ 57
CHECKING TEMPERATURE DECREASE ......... 57
CHECKING TEMPERATURE INCREASE .......... 58
CHECK A/C SWITCH .......................................... 58
CHECKING AUTO MODE ................................... 58
Operational Check (Rear) ....................................... 59
CHECKING BLOWER ......................................... 59
CHECKING TEMPERATURE DECREASE ......... 59
CHECKING TEMPERATURE INCREASE .......... 59
Power Supply and Ground Circuit for Front Air Con-
trol ........................................................................... 60
INSPECTION FLOW ........................................... 60
COMPONENT DESCRIPTION ............................ 61
DIAGNOSTIC PROCEDURE FOR A/C SYSTEM ... 61
Mode Door Motor Circuit ........................................ 63
INSPECTION FLOW ........................................... 63
SYSTEM DESCRIPTION .................................... 64
COMPONENT DESCRIPTION ............................ 65
DIAGNOSTIC PROCEDURE FOR MODE
DOOR MOTOR ................................................... 65
Air Mix Door Motor Circuit ...................................... 67
INSPECTION FLOW ........................................... 67
SYSTEM DESCRIPTION .................................... 68
COMPONENT DESCRIPTION ............................ 69
DIAGNOSTIC PROCEDURE FOR AIR MIX
DOOR MOTOR (DRIVER) ................................... 69
DIAGNOSTIC PROCEDURE FOR AIR MIX
DOOR MOTOR (PASSENGER) .......................... 71
DIAGNOSTIC PROCEDURE FOR AIR MIX
DOOR MOTOR (REAR) ...................................... 73
Intake Door Motor Circuit ........................................ 76
INSPECTION FLOW ........................................... 76
SYSTEM DESCRIPTION .................................... 77
COMPONENT DESCRIPTION ............................ 78
DIAGNOSTIC PROCEDURE FOR INTAKE DOOR MOTOR ....................................................78
Defroster Door Motor Circuit ...................................79
SYMPTOM: ..........................................................79
INSPECTION FLOW ............................................79
SYSTEM DESCRIPTION .....................................80
COMPONENT DESCRIPTION ............................80
DIAGNOSTIC PROCEDURE FOR
DEFROSTER DOOR MOTOR .............................81
Front Blower Motor Circuit ......................................83
INSPECTION FLOW ............................................83
SYSTEM DESCRIPTION .....................................84
COMPONENT DESCRIPTION ............................85
DIAGNOSTIC PROCEDURE FOR BLOWER
MOTOR ................................................................85
COMPONENT INSPECTION ...............................89
Rear Blower Motor Circuit .......................................90
INSPECTION FLOW ............................................90
SYSTEM DESCRIPTION .....................................91
DIAGNOSTIC PROCEDURE FOR REAR
BLOWER MOTOR ...............................................91
COMPONENT INSPECTION ...............................99
Rear Air Control Circuit ......................................... 101
INSPECTION FLOW .......................................... 101
SYSTEM DESCRIPTION ................................... 102
DIAGNOSTIC PROCEDURE FOR REAR AIR
CONTROL ......................................................... 102
Magnet Clutch Circuit ............................................ 104
INSPECTION FLOW .......................................... 104
SYSTEM DESCRIPTION ................................... 105
DIAGNOSTIC PROCEDURE FOR MAGNET
CLUTCH ............................................................ 105
Insufficient Cooling ................................................110
INSPECTION FLOW ..........................................110
PERFORMANCE TEST DIAGNOSES .............. 111
PERFORMANCE CHART ..................................113
TROUBLE DIAGNOSES FOR UNUSUAL PRES-
SURE .................................................................114
Insufficient Heating ...............................................117
INSPECTION FLOW ..........................................117
Noise .....................................................................118
INSPECTION FLOW ..........................................118
Self-diagnosis ....................................................... 120
INSPECTION FLOW .......................................... 120
Memory Function .................................................. 121
INSPECTION FLOW .......................................... 121
Water Valve Circuit ................................................ 121
COMPONENT DESCRIPTION .......................... 121
DIAGNOSTIC PROCEDURE FOR WATER
VALVE ................................................................ 122
COMPONENT INSPECTION ............................. 124
Ambient Sensor Circuit ......................................... 125
COMPONENT DESCRIPTION .......................... 125
AMBIENT TEMPERATURE INPUT PROCESS . 125
DIAGNOSTIC PROCEDURE FOR AMBIENT
SENSOR ............................................................ 125
COMPONENT INSPECTION ............................. 127
In-vehicle Sensor Circuit ....................................... 128
COMPONENT DESCRIPTION .......................... 128
DIAGNOSTIC PROCEDURE FOR IN-VEHICLE

ATC-22
LUBRICANT
Revision: August 20072004 QX56
LUBRICANTPFP:KLG00
Maintenance of Lubricant Quantity in CompressorEJS002BV
The lubricant in the compressor circulates through the system with the refrigerant. Add lubricant to compres-
sor when replacing any component or after a large refrigerant leakage has occurred. It is important to maintain
the specified amount.
If lubricant quantity is not maintained properly, the following malfunctions may result:

Lack of lubricant: May lead to a seized compressor

Excessive lubricant: Inadequate cooling (thermal exchange interference)
LUBRICANT
Name: NISSAN A/C System Lubricant Type S (DH-PS)
Part number: KLH00-PAGS0
CHECKING AND ADJUSTING
CAUTION:
If excessive lubricant leakage is noted, do not perform the lubricant return operation.
Start the engine and set the following conditions:
test condition

Engine speed: Idling to 1,200 rpm

A/C switch: On

Blower speed: Max. position

Temp. control: Optional [Set so that intake air temperature is 25 to 30° C (77 to 86°F).]

Intake position: Recirculation ( )

Perform lubricant return operation for about ten minutes
Adjust the lubricant quantity according to the following table.
Lubricant Adjusting Procedure for Components Replacement Except Compressor
After replacing any of the following major components, add the correct amount of lubricant to the system.
Amount of Lubricant to be Added
*1: If refrigerant leak is small, no addition of lubricant is needed.
Lubricant Adjustment Procedure for Compressor Replacement
1. Before connecting recovery/recycling equipment to vehicle, check recovery/recycling equipment gauges.
No refrigerant pressure should be displayed. If NG, recover refrigerant from equipment lines.
2. Connect recovery/recycling equipment to vehicle. Confirm refrigerant purity in supply tank using recovery/
recycling equipment and refrigerant identifier. If NG, refer to AT C - 5 , "
Contaminated Refrigerant" .
3. Confirm refrigerant purity in vehicle A/C system using recovery/recycling equipment and refrigerant identi-
fier. If NG, refer to AT C - 5 , "
Contaminated Refrigerant" .
4. Discharge refrigerant into the refrigerant recovery/recycling equipment. Measure lubricant discharged into
the recovery/recycling equipment.
5. Drain the lubricant from the “old” (removed) compressor into a graduated container and recover the
amount of lubricant drained.
6. Drain the lubricant from the “new” compressor into a separate, clean container.
Part replacedLubricant to be added to system
Remarks
Amount of lubricant
m (US fl oz, Imp fl oz)
Front evaporator 75 (2.5, 2.6) —
Rear evaporator 75 (2.5, 2.6) —
Condenser 75 (2.5, 2.6) —
Liquid tank 5 (0.2, 0.2) Add if compressor is not replaced.
In case of refrigerant leak30 (1.0, 1.1) Large leak
— Small leak *1

ATC-24
AIR CONDITIONER CONTROL
Revision: August 20072004 QX56
AIR CONDITIONER CONTROLPFP:27500
DescriptionEJS002BW
The front air control provides automatic regulation of the vehicle's interior temperature. The system is based
on the driver's and passenger's selected "set temperature", regardless of the outside temperature changes.
This is done by utilizing a microcomputer that is part of the front air control, which receives input signals from
the following five sensors:

Ambient sensor

In-vehicle sensor

Intake sensor

Optical sensor (one sensor for driver and passenger side)

PBR (position balanced resistor)
The front air control uses these signals (including the set temperature) to automatically control:

Outlet air volume

Air temperature

Air distribution
The front air control also provides separate regulation of the vehicle's interior temperature for the rear passen-
ger area. The system is based on the temperature and rear blower settings selected on the front air control
rear fan switch (front) and rear temperature/mode dial (front), or from the rear fan switch (rear) and rear tem-
perature/mode dial (rear) on the rear air control, when the rear fan switch (front) is set to the rear (R) position.
The front air control or rear air control is used to select:

Outlet air volume

Air temperature/mode distribution
OperationEJS002BX
AIR MIX DOORS CONTROL
The air mix doors are automatically controlled so that in-vehicle temperature is maintained at a predetermined
value by the temperature setting, ambient temperature, in-vehicle temperature and amount of sunload.
FAN SPEED CONTROL
Blower speed is automatically controlled based on temperature setting, ambient temperature, in-vehicle tem-
perature, intake temperature, amount of sunload and air mix door position.
When AUTO switch is pressed, the blower motor starts to gradually increase air flow volume (if required).
When engine coolant temperature is low, the blower motor operation is delayed to prevent cool air from flow-
ing.
INTAKE DOOR CONTROL
The intake door is automatically controlled by the temperature setting, ambient temperature, in-vehicle tem-
perature, intake temperature, amount of sunload and ON-OFF operation of the compressor.
MODE DOOR CONTROL
The mode door is automatically controlled by the temperature setting, ambient temperature, in-vehicle temper-
ature, intake temperature and amount of sunload.
DEFROSTER DOOR CONTROL
The defroster door is controlled by turning the defroster dial to front defroster.

ATC-54
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
Using Confirmation/Adjustment Mode (NAVI)
NOTE:
Ambient temperature must be at least 10° C (50° F) to run self-diagnosis.
1. Start engine.
2. Turn the audio system off.
3. While pressing the "PAUSE/MUTE" button, turn the volume con-
trol dial clockwise or counterclockwise for 30 clicks or more.
(When the self diagnosis mode is started, a short beep will be
heard.)

Shifting from current screen to previous screen is performed
by pressing "PREV" button.
4. The initial self-diagnosis screen will be shown, and items "Self-
Diagnosis (DCU)", "Self-Diagnosis (NAVI)", "Confirmation/
Adjustment" and "CAN DIAG SUPPORT MONITOR" will
become selective.
5. When "Confirmation/Adjustment" is selected on the initial self-
diagnosis screen, the operation will enter CONFIRMATION/
ADJUSTMENT mode. In this mode, check and adjustment of
each item will become possible.
6. The initial trouble diagnosis screen will be shown, and items
"display Diagnosis", "Vehicle Signals", "Auto Climate Control"
and "Navigation" will become selective.
7. Select the "Auto Climate Control" switch on "CONFIRMATION/
ADJUSTMENT" screen to display the "Auto Climate Control"
diagnosis screen to begin diagnosis The front blower speed indi-
cation bars will flash and the ambient temperature display will
indicate 0° during the self-diagnosis. Fault codes (if any are
present) will be displayed in the ambient temperature display area. Refer to ATC-55, "
SELF-DIAGNOSIS
CODE CHART" .
WKIA1504E
SKIA4207E
SKIA4220E

ATC-84
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
SYSTEM DESCRIPTION
Component Parts
Blower speed control system components are:

Front air control

Front blower motor

In-vehicle sensor

Ambient sensor

Optical sensor

Intake sensor
System Operation
Automatic Mode
In the automatic mode, the blower motor speed is calculated by the front air control and variable blower control
based on input from the in-vehicle sensor, optical sensor, intake sensor and ambient sensor, and potentio tem-
perature control (PTC).
When the air flow is increased, the duty ratio of the blower motor′s drive signal is changed at 8%/sec. to pre-
vent a sudden increase in air flow.
In addition to manual air flow control and the usual automatic air flow control, starting air flow control, low
water temperature starting control and high passenger compartment temperature starting control are avail-
able.
Starting Blower Speed Control
Start up from cold soak condition (Automatic mode).
In a cold start up condition where the engine coolant temperature is below 50°C (122°F), the blower will not
operate at blower speed 1 for a short period of time (up to 210 seconds). The exact start delay time varies
depending on the ambient and engine coolant temperatures.
In the most extreme case (very low ambient temperature) the blower starting delay will be 210 seconds as
described above. After the coolant temperature reaches 50°C (122°F), or the 210 seconds has elapsed, the
blower speed will increase to the objective blower speed.
Start up from normal operating or hot soak condition (Automatic mode).
The blower will begin operation momentarily after the AUTO switch is pushed. The blower speed will gradually
rise to the objective speed over a time period of 3 seconds or less (actual time depends on the objective
blower speed).
WJIA0440E

TROUBLE DIAGNOSIS
ATC-121
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Revision: August 20072004 QX56
Memory FunctionEJ S00 2CQ
SYMPTOM: Memory function does not operate.
INSPECTION FLOW
Water Valve CircuitEJS002CR
COMPONENT DESCRIPTION
Water Valve
The water valve cuts the flow of engine coolant to the front and rear
heater cores to allow for maximum cooling during A/C operation. It is
controlled by the front air control through the water valve relay.
*1ATC-60, "Power Supply and Ground
Circuit for Front Air Control"
*2AT C - 5 6 , "Operational Check (Front)"*3AT C - 5 3 , "A/C System Self-diagnosis
Function"
WJIA0797E
WJIA1015E