2004 INFINITI QX56 Ins

PREPARATION
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Revision: August 20072004 QX56
Commercial Service ToolsEDS0017I
Tool nameDescription
Flange wrench Removing and installing companion flange
PullerRemoving companion flange
Pin punchRemoving and installing retainer pin
a: 6 mm (0.24 in) dia.
Power toolRemoving transfer case assembly
NT771
NT077
NT410
PBIC0190E

TF-8
PRECAUTIONS
Revision: August 20072004 QX56
PRECAUTIONSPFP:00001
Precautions for Supplemental Restraint System (SRS) “AIR BAG” and “SEAT
BELT PRE-TENSIONER”
EDS0017J
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.
PrecautionsEDS0017K

Before connecting or disconnecting the transfer control
unit harness connector, turn ignition switch OFF and dis-
connect negative battery terminal. Failure to do so may
damage the transfer control unit. Because battery voltage is
applied to transfer control unit even if ignition switch is
turned off.

When connecting or disconnecting pin connectors into or
from transfer control unit, take care not to damage pin ter-
minals (bend or break).
Make sure that there are not any bends or breaks on trans-
fer control unit pin terminal, when connecting pin connec-
tors.

Before replacing transfer control unit, perform transfer con-
trol unit input/output signal inspection and make sure
whether transfer control unit functions properly or not. (See
page TF-55
.)
SEF 2 89 H
SEF 2 91 H
MEF040DB

PRECAUTIONS
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Revision: August 20072004 QX56
Service NoticeEDS0017L
1. Before proceeding with disassembly, thoroughly clean the outside of the all-mode 4WD transfer. It is
important to prevent the internal parts from becoming contaminated by dirt or other foreign matter.
2. Disassembly should be done in a clean work area.
3. Use lint-free cloth or towels for wiping parts clean. Common shop rags can leave fibers that could interfere
with the operation of the all-mode 4WD transfer.
4. Place disassembled parts in order for easier and proper assembly.
5. All parts should be carefully cleaned with a general purpose, non-flammable solvent before inspection or
reassembly.
6. Gaskets, seals and O-rings should be replaced any time the all-mode 4WD transfer is disassembled.
7. It is very important to perform functional tests whenever they are indicated.
8. The valve body contains precision parts and requires extreme care when parts are removed and serviced.
Place removed parts in a parts rack in order to replace them in correct positions and sequences. Care will
also prevent springs and small parts from becoming scattered or lost.
9. Properly installed valves, sleeves, plugs, etc. will slide along bores in valve body under their own weight.
10. Before assembly, apply a coat of recommended ATF to all parts. Apply petroleum jelly to protect O-rings
and seals, and to hold bearings and washers in place during assembly. Do not use grease.
11. Extreme care should be taken to avoid damage to O-rings, seals and gaskets when assembling.
12. After overhaul, refill the transfer with new ATF.
13. When the all-mode 4WD transfer drain plug is removed, only some of the fluid is drained. Old all-mode
4WD transfer fluid will remain in torque converter and ATF cooling system. Always follow the proper pro-
cedure. Refer to MA-24, "
Changing Transfer Fluid" .
Wiring Diagrams and Trouble DiagnosisEDS001CE
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".

ALL-MODE 4WD SYSTEM
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Revision: August 20072004 QX56
Description of Electrical PartsEDS0017R
TRANSFER MOTOR
1. The transfer motor drives the sub-oil pump to provide proper lubrication and oil pressure control when the
vehicle is at standstill, during low-speed operations or is being driven in reverse.
2. The main oil pump is operated by the driving force of the mainshaft. In other words, sufficient oil pressure
buildup does not occur when the vehicle is at standstill or during low-speed operations. While the vehicle
is being driven in reverse, the main oil pump rotates in the reverse direction. Therefore the main oil pump
does not discharge oil pressure. During any of the above vehicle operations, the transfer motor drives the
sub-oil pump to compensate for insufficient oil pressure.
3. The transfer motor operates as follows:
1. The motor relay turns OFF in the 2WD mode.
2. The motor relay operates as described in the table below in modes other than the 2WD mode.
Ta b l e 1
Ta b l e 2
NOTE:
OFF (after 2.5 seconds have elapsed.)
4. 4WD shift switch, PNP switch, Neutral-4LO switch, vehicle speed sensor and throttle position sensor are
used in conjunction with the transfer motor.
WAIT DETECTION SWITCH
1. The wait detection switch releases the “booming” torque produced in the propeller shaft. After the release
of the “booming” torque, the wait detection switch helps provide the 4WD lock gear (clutch drum) shifts. A
difference may occur between the operation (“4LO” to “4H” shift only) of the 4WD shift switch and actual
drive mode. At this point, the wait detection switch senses an actual drive mode.
2. The wait detection switch operates as follows:
4WD lock gear (clutch drum) locked: ON
4WD lock gear (clutch drum) released: OFF
3. The wait detection switch senses an actual drive mode and the 4WD shift indicator lamp indicates the
vehicle drive mode.
2-4WD SHIFT SOLENOID VALVE
The 2-4WD shift solenoid valve operates to apply oil pressure to the wet, multiplate clutch, depending on the
drive mode. The driving force is transmitted to the front wheels through the clutch when the vehicle is set in the
4WD mode. Setting the vehicle in the 2WD mode requires no pressure buildup. In other words, pressure force
applied to the wet, multiplate clutch becomes zero.
PNP switch “R” position VFF (Vehicle speed) A/T position Motor relay drive command
ON — R ON
OFF0Positions other than the “P” or
“N” positionsON
—“P” or “N” position (See Table
2.)—
0 < VFF ≤ 50 km/h (31 MPH) — ON
50 km/h (31 MPH) < VFF < 55
km/h (34 MPH)—HOLD
55 km/h (34 MPH) ≤ VFF — OFF
A/T position N-4L SW 4WD modeThrottle position
0 - 0.07/8 0.07/8 - 1/8 1/8 - MAX
NOFFLOCK (4H) ON ON ON
Positions other than
the LOCK position
(2WD or AUTO)See NOTE. HOLD ON
ON — See NOTE. HOLD ON
P——See NOTE.HOLDON

ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
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Flickering pattern or flick-
ering conditionMalfunction Check items
2 Rear revolution sensor circuit is shorted or open.Refer to AT- 11 2 , "
DTC P0720 VEHI-
CLE SPEED SENSOR A/T (REVO-
LUTION SENSOR)" .
3 4WD solenoid valve circuit is shorted or open.Refer to TF-60, "
Diagnostic Proce-
dure" .
42-4WD shift solenoid valve circuit is shorted or 2WD switch of
4WD shift switch is shorted.Refer to TF-62, "
Diagnostic Proce-
dure" .
5 Transfer motor relay circuit is shorted or open.Refer to TF-64, "
Diagnostic Proce-
dure" .
6If unexpected signal is detected because of ABS wheel sensor
malfunction or communications error within the vehicle.Refer to BRC-38, "
Wheel Sensor
System Inspection" .
7 When malfunction in CAN communication system is detected.Refer to LAN-5, "
CAN COMMUNICA-
TION" .
8 A/D converter of transfer control unit functions improperly.Refer to EC-351, "
DTC P0605 ECM"
.
9 Transfer fluid temperature sensor circuit is open.Refer to TF-66, "
Diagnostic Proce-
dure" .
10 Neutral-4LO switch circuit is shorted or open.Refer to TF-69, "
Diagnostic Proce-
dure" .
112-4WD shift solenoid valve circuit, 2WD switch of 4WD shift
switch circuit or clutch pressure switch circuit is shorted or open.Refer to TF-62, "
Diagnostic Proce-
dure" or TF-72, "Diagnostic Proce-
dure" .
12 Line pressure switch circuit is shorted or open.Refer to TF-74, "
Diagnostic Proce-
dure" .
13 Engine speed signal circuit is shorted or open.Refer to AT- 11 5 , "
DTC P0725
ENGINE SPEED SIGNAL" .
14 Throttle position sensor circuit is shorted or open.Refer to EC-351, "
DTC P0605 ECM"
.
15 Malfunction in power supply circuit of transfer control unit. Power supply of transfer control unit
16 4WD shift switch circuit is shorted.Refer to TF-62, "
Diagnostic Proce-
dure" .
17 ABS operation signal circuit is shorted.Refer to BRC-54, "
CAN Communica-
tion System Inspection" .
18ATP switch, wait detection switch or neutral-4LO switch circuit is
shorted or open.Refer to TF-69, "
Diagnostic Proce-
dure" .
19Transfer control device actuator motor is malfunctioning. (Mal-
functions are detected when actuator motor fails to operate while
shifting from “4H” to “4LO” or vice versa.)Refer to TF-77, "
Diagnostic Proce-
dure" or TF-82, "Diagnostic Proce-
dure" .
20Transfer control device actuator motor arm position sensing
switch is malfunctioning.Refer to TF-80, "
Diagnostic Proce-
dure" or TF-82, "Diagnostic Proce-
dure" .
21Transfer control device actuator circuit is shorted or open. (Mal-
functions are detected when motor relay circuit is open/shorted or
relay monitor circuit is open/shorted.)Refer to TF-77, "
Diagnostic Proce-
dure" , TF-80, "Diagnostic Proce-
dure" or TF-82, "Diagnostic
Procedure" .
22If VDC operation signal is being input because of VDC malfunc-
tion or communication error within the vehicle.Refer to BRC-40, "
ABS/TCS/VDC
Control Unit Inspection" .
23If TCS operation signal is being input because of TCS malfunction
or communication error within the vehicle.Refer to BRC-40, "
ABS/TCS/VDC
Control Unit Inspection" .
24If unexpected signal is input because of AT PNP switch circuit or
communication error within the vehicle.Refer to AT- 1 0 9 , "
DTC P0705 PARK/
NEUTRAL POSITION SWITCH" .
Repeats flickering every
2 to 5 sec.Circuits that the self-diagnosis covers have no malfunction. —

ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
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CONSULT-II Function (ALL MODE AWD/4WD)EDS002G7
CONSULT-II can display each diagnostic item using the diagnostic test modes shown following.
Trouble Diagnosis with CONSULT-IIEDS0017V
SELF-DIAGNOSIS
CONSULT-II Setting Procedure
1. Turn ignition switch to “OFF” position.
CAUTION:
If CONSULT-II is used with no connection of CONSULT-II CONVERTER, malfunctions might be
detected in self-diagnosis depending on control unit which carry out CAN communication.
2. Connect CONSULT-II and CONSULT-II CONVERTER to data
link connector.
3. Start engine.
4. On CONSULT-II screen, touch “START (NISSAN BASED
VHCL)”.
5. Touch “ALL MODE AWD/4WD” on SELECT SYSTEM screen.
If "ALL MODE AWD/4WD" is not indicated, refer to GI-39,
"CONSULT-II Data Link Connector (DLC) Circuit" .
ALL MODE AWD/4WD diag-
nostic modeDescription
SELF-DIAG RESULTS Displays transfer control unit self-diagnosis results.
DATA MONITOR Displays transfer control unit input/output data in real time.
WORK SUPPORTSupports inspections and adjustments. Commands are transmitted to the transfer control unit for set-
ting the status suitable for required operation, input/output signals are received from the transfer con-
trol unit and received data is displayed.
CAN DIAG SUPPORT
MNTRThe results of transmit/receive diagnosis of CAN communication can be read.
ECU PART NUMBER Transfer control unit part number can be read.
BBIA0369E
BCIA0029E
BCIA0030E

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ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
Revision: August 20072004 QX56
6. Touch “SELF-DIAG RESULTS” on SELECT DIAG MODE
screen.
7. Self-diagnostic results are displayed.
SELF-DIAGNOSTIC ITEMS
BCIA0031E
Detected items
(Screen terms for CONSULT-II,
“SELF-DIAG RESULT” mode)Malfunction is detected when... Check items
Revolution sensor (rear)
(VHCL SPEED SEN·RR)

Signal from vehicle speed sensor 1 (installed on A/T) is
not input due to open circuit.

Improper signal is input while driving.Refer to AT- 11 2 , "
DTC P0720
VEHICLE SPEED SENSOR A/T
(REVOLUTION SENSOR)" .
4WD solenoid valve
(DUTY SOLENOID)

Proper voltage is not applied to solenoid valve due to
open or short circuit.Refer to TF-60, "
Diagnostic Proce-
dure" .
2-4WD shift solenoid valve
(2-4WD SOLENOID)Refer to TF-62, "
Diagnostic Proce-
dure" .
Tran s fe r mo to r re lay
(MOTOR RELAY)

Motor does not operate properly due to open or short cir-
cuit in transfer motor or motor relay.Refer to TF-64, "Diagnostic Proce-
dure" .
Transfer fluid temperature sensor
(FLUID TEMP SENSOR)

Signal voltage from fluid temperature sensor is abnor-
mally high (T/F fluid temperature is abnormally low)
while driving.Refer to TF-66, "Diagnostic Proce-
dure" .
Neutral-4LO switch
(N POSI SW TF)

Improper signal is input while driving.Refer to TF-69, "Diagnostic Proce-
dure" .
Clutch pressure
(CLUTCH PRESSURE)

Improper signal is input due to open or short circuit.

Malfunction occurs in clutch pressure hydraulic circuit.(*1) Refer to TF-72, "
Diagnostic
Procedure" .
Line pressure
(LINE PRESSURE)

Improper signal is input due to open or short circuit.

Malfunction occurs in line pressure hydraulic circuit.(*1) Refer to TF-74, "
Diagnostic
Procedure" .
Engine speed signal (Note 1)
(ENGINE SPEED SIG)

Engine speed is abnormally low while driving.Refer to AT- 11 5 , "DTC P0725
ENGINE SPEED SIGNAL" .
Throttle position sensor
(THRTL POSI SEN)

Signal voltage from throttle position sensor is abnormally
high.

Signal voltage from throttle position sensor is abnormally
low when closed throttle position switch is OFF.Refer to EC-351, "
DTC P0605
ECM" .
Transfer control unit (ADC)
C/U (ADC)/THRTL SEN

Power supply voltage for A/D converter system of trans-
fer control unit is malfunctioning.Refer to EC-351, "DTC P0605
ECM" .
Battery voltage (Note 1)
(BATTERY VOLTAGE)

Power supply voltage for transfer control unit is abnor-
mally low while driving.Refer to TF-18, "Wiring Diagram —
T/F —" .
4WD shift switch
(4WD MODE SW)

More than two switch inputs are simultaneously detected
due to short circuit of 4WD shift switch.Refer to TF-62, "Diagnostic Proce-
dure" .
ABS operation signal (Note 4)
(ABS OPER SIGNAL)

When a malfunction signal due to disconnection or
shorting is detected.

When a defect signal is entered from the ABS control
unit.Refer to BRC-54, "
CAN Communi-
cation System Inspection" .
Wait detection switch (Note 2)
(WAIT DETECT SWITCH)

Improper signal is input due to open or short circuit.(*2) Refer to TF-69, "Diagnostic
Procedure" .

ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
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Note 1: When a malfunction occurs, it is only displayed and not stored in the memory.
Note 2: When the wait detection switch has been properly fixed, malfunction information is erased from the memory.
Note 3: If 4WD shift switch is left between 4H and 4LO for a while, this indication may be displayed.
(*1): If the malfunction is detected only while driving in reverse, check the continuity of “R” position on A/T PNP switch. When there is
nothing wrong with the electrical system, check the hydraulic system.
(*2): If a revolution sensor malfunction is detected at the same time, check the revolution sensor circuit first.
Note 4: When this malfunction is detected with the ABS warning lamp off, first check for disconnection or shorting in the harness
between the transfer control unit and the ABS control unit.
Note 5: When several systems including CAN communication system indicate malfunctions, perform diagnosis of the CAN communica-
tion first.Shift actuator abnormal
(SHIFT ACT)Transfer control device actuator motor is malfunctioning.
(Malfunctions are detected when actuator motor fails to
operate while shifting from “4H” to “4LO” or vice versa.) Refer to TF-77, "
Diagnostic Proce-
dure" or TF-82, "Diagnostic Pro-
cedure" .
Shift actuator position switch
abnormal
(SHIFT ACT P/S)Transfer control device actuator motor arm position sens-
ing switch is malfunctioning.Refer to TF-80, "
Diagnostic Proce-
dure" or TF-82, "Diagnostic Pro-
cedure" .
Shift actuator circuit abnormal
(SHIFT ACT CIR)Transfer control device actuator circuit is shorted or open.
(Malfunctions are detected when motor relay circuit is
open/shorted or relay monitor circuit is open/shorted.)Refer to TF-77, "
Diagnostic Proce-
dure" , TF-80, "Diagnostic Proce-
dure"TF-82, "Diagnostic
Procedure" .
Memory power supply stop

Due to removal of battery which cuts off power supply to
transfer control unit, self-diagnosis memory function is
suspended.Refer to TF-76, "Diagnostic Proce-
dure" .
Transfer control unit (RAM)
[CONTROL UNIT (RAM)]

Malfunction is detected in the memory (RAM) system of
transfer control unit.—
Transfer control unit (ROM)
[CONTROL UNIT (ROM)]

Malfunction is detected in the memory (ROM) system of
transfer control unit.—
Transfer control unit (EEPROM)
[CONTROL UNIT (EEPROM)]

Malfunction is detected in the memory (EEPROM) sys-
tem of transfer control unit.—
Longitudinal G-sensor Displayed, but do not use. —
ABS VHL SPD SEN

ABS vehicle speed sensor signal is not input due to an
open circuit.

An unexpected signal is input when vehicle is being
driven.Refer to ABS vehicle speed sensor
diagnosis.
STEERING ANGLE SENSOR Displayed, but do not use. —
VDC OPER SIGIf VDC operation signal is being input because of VDC
malfunction or communication error within the vehicle.Refer to BRC-40, "
ABS/TCS/VDC
Control Unit Inspection" .
TCS OPER SIGIf TCS operation signal is being input because of TCS mal-
function or communication error within the vehicle.Refer to BRC-40, "
ABS/TCS/VDC
Control Unit Inspection" .
CAN COMM (Note 5) Malfunction is detected in CAN communication.Refer to LAN-5, "
CAN COMMUNI-
CATION" .
A/T POSITION SIGNALWhen AT PNP switch circuit is malfunction or communica-
tion error between the vehiclesRefer to AT-109, "
DTC P0705
PARK/NEUTRAL POSITION
SWITCH" . Detected items
(Screen terms for CONSULT-II,
“SELF-DIAG RESULT” mode)Malfunction is detected when... Check items