2008 INFINITI QX56 ECO mode

4WD SYSTEMDLN-15
< FUNCTION DIAGNOSIS > [ATX14B]
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TRANSFER FLUID TEMPERATURE SENSOR
The transfer fluid temperature sensor detects the trans fer fluid temperature and sends a signal to the transfer
control unit.
TRANSFER MOTOR
• The transfer motor drives the sub-oil pump to provi de proper lubrication and oil pressure control when the
vehicle is at standstill, during low-speed operations or is being driven in reverse.
• The main oil pump is operated by the driving force of t he mainshaft. In other words, sufficient oil pressure
buildup does not occur when the vehicle is at standsti ll 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 vehi cle operations, the transfer motor drives the sub-oil
pump to compensate for insufficient oil pressure.
• The transfer motor operates as follows:
- The motor relay turns OFF in the 2WD mode.
- The motor relay operates as described in the table below in modes other than the 2WD mode.
• 4WD shift switch, transmission range switch, Neutral-4LO switch, vehicle speed sensor and throttle position
sensor are used in conjunction with the transfer motor.
Transfer Motor Relay Operation
*: After 2.5 seconds have elapsed.
CLUTCH PRESSURE SOLENOID VALVE
The clutch pressure solenoid valve distributes front and rear torque in AUTO 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 so 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.
TRANSFER CONTROL DEVICE
Integrates actuator motor and actuator position switch.
4WD shift switch A/T selector lever position Vehicle speed
(VSS) Accelerator pedal position Motor relay drive
command
2WD ———OFF
4H (LOCK) and 4LO N position
0— ON
P position 00 - 0.07/8
OFF*
0.07/8 - 1/8 HOLD
1/8 - MAX ON
Other than R position 0 < VSS ≤
50 km/h (31 MPH)
— ON
50 km/h (31 MPH) < VSS < 55 km/h (34 MPH) HOLD
55 km/h (34 MPH) ≤ VSS OFF
R position —— ON
R position —— ON
AUTO P or N position 0
0 - 0.07/8
OFF*
0.07/8 - 1/8 HOLD
1/8 - MAX ON
0 < VSS ≤ 50 km/h (31 MPH)
— ON
50 km/h (31 MPH) < VSS < 55 km/h (34 MPH) HOLD
55 km/h (34 MPH) ≤ VSS OFF
Other than R, P and N posi-
tion 0 < VSS ≤
50 km/h (31 MPH)
— ON
50 km/h (31 MPH) < VSS < 55 km/h (34 MPH) HOLD
55 km/h (34 MPH) ≤ VSS OFF
Revision: March 2010 2008 QX56

DLN-20
< FUNCTION DIAGNOSIS >[ATX14B]
DIAGNOSIS SYSTEM (T
RANSFER CONTROL UNIT)
4L SW [ON/OFF] ×–×4WD shift switch status is displayed.
(4L means 4LO of 4WD shift switch.)
N POSI SW TF [ON/OFF] ×–×Neutral-4LO switch signal status is displayed.
ATP SWITCH [ON/OFF] ×–×ATP switch signal status is displayed.
WAIT DETCT SW [ON/OFF] ×–×Wait detection switch status is displayed.
LINE PRES SW [ON/OFF] ×–×Line pressure switch status is displayed.
CL PRES SW [ON / OFF] ×–×Clutch pressure switch status is displayed.
N POSI SW AT [ON/OFF] ×–×N position signal of A/T transmission range
switch status is displayed.
Signal input with CAN communication line.
R POSI SW AT [ON/OFF] ×–×R position signal of A/T transmission range
switch status is displayed.
Signal input with CAN communication line.
P POSI SW AT [ON/OFF] ×–×P position signal of A/T transmission range
switch status is displayed.
Signal input with CAN communication line.
ABS OPER SW [ON/OFF] ×–×ABS operation signal status is displayed.
Signal input with CAN communication line.
VDC OPER SW [ON/OFF] ×–×VDC operation signal status is displayed.
Signal input with CAN communication line.
TCS OPER SW [ON/OFF] ×–×TCS operation signal status is displayed.
Signal input with CAN communication line.
THROTTLE POSI [0.0/8] –×× Thottle position status is displayed.
Signal input with CAN communication line.
4WD MODE [AUTO/LOCK/2WD/4L] – ××Control status of 4WD recognized by transfer
control unit. (AUTO, 4H, 2WD or 4LO)
VHCL/S COMP [km/h] or [mph] –×× Vehicle speed recognized by transfer control
unit.
COMP CL TORQ [kgm] –×× Calculated torque recognized by transfer con-
trol unit.
DUTY SOLENOID [%] –×× Control value of clutch pressure solenoid.
2-4WD SOL [ON/OFF] –×× Output condition to 2-4WD solenoid.
2-4WD SOL MON [ON/OFF] ––×Check signal for transfer control unit signal
output.
MOTOR RELAY [ON/OFF] –×× Transfer motor relay signal status is dis-
played.
MOTOR RELAY MON [ON/OFF] ––×Check signal for transfer control unit signal
ou
tpu
t

.
4WD FAIL LAMP [ON/OFF] –×× Control status of 4WD warning lamp is dis-
played.
2WD IND [ON/OFF] ––×Control status of 4WD shift indicator lamp
(2WD indicator lamp) is displayed.
AUTO IND [ON/OFF] ––×Control status of 4WD shift indicator lamp
(2WD and AUTO indicator lamp) is displayed.
LOCK IND [ON/OFF] ––×Control status of 4WD shift indicator lamp
(2WD, AUTO and Lock indicator) is displayed.
4L IND [ON/OFF] –– ×Control status of 4LO indicator lamp is dis-
played.
Monitored item (Unit)
Monitor item selection
Remarks
ECU INPUT
SIGNALS MAIN
SIGNALS SELEC-
TION FROM
MENU
Revision: March 2010 2008 QX56

DLN-24
< COMPONENT DIAGNOSIS >[ATX14B]
P1802 – P1804, P1809 TRANSFER CONTROL UNIT
P1802 – P1804, P1809 TRANSFER CONTROL UNIT
DescriptionINFOID:0000000001737105
The transfer control unit controls the transfer contro
l device which controls shifts between AUTO, 4H and 4LO
and between 2WD and 4WD. A DTC may set when any of the following occur:
• Malfunction is detected in the memory (RAM) system of transfer control unit.
• Malfunction is detected in the memory (ROM) system of transfer control unit.
• Malfunction is detected in the memory (E EPROM) system of transfer control unit.
• AD converter system of transfer control unit is malfunctioning.
DTC LogicINFOID:0000000001737106
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE
1.DTC CONFIRMATION PROCEDURE
1. Turn ignition switch ON.
2. Perform self-diagnosis.
Are DTC's P1802 - P1804 or P1809 detected?
YES >> Perform diagnosis procedure. Refer to DLN-24, "Diagnosis Procedure".
NO >> Inspection End.
Diagnosis ProcedureINFOID:0000000001737107
1.INSPECTION START
Do you have CONSULT-III?
YES or NO
YES >> GO TO 2.
NO >> GO TO 3.
2.PERFORM SELF-DIAGNOSIS (WITH CONSULT-III)
With CONSULT-III
1. Turn ignition switch ON. (Do not start engine.)
2. Select SELF-DIAG RESULTS mode for ALL MODE AWD/4WD with CONSULT-III.
3. Touch ERASE.
4. Turn ignition switch OFF and wait at least 10 seconds.
5. Perform the self-diagnosis again.
Is the CONTROL UNIT 1 [P1802], CONTROL UNIT 2 [P1803], CONTRO L UNIT 3 [P1804] or CONTROL
UNIT 4 [P1809] displayed?
YES >> Replace transfer control unit. Refer to DLN-128, "Removal and Installation".
NO >> Inspection End.
3.PERFORM SELF-DIAGNOSIS (WITHOUT CONSULT-III)
DTC CONSULT-III Diagnostic item is detected when... Reference
[P1802] CONTROL UNIT 1 Malfunction is detected in the memory
(RAM) system of transfer control unit.
Refer to DLN-24
.
[P1803] CONTROL UNIT 2
Malfunction is detected in the memory
(ROM) system of transfer control unit.
[P1804] CONTROL UNIT 3 Malfunction is detected in the memory
(EEPROM) system of transfer control
unit.
[P1809] CONTROL UNIT 4 AD converter system of transfer control
unit is malfunctioning.
Revision: March 2010
2008 QX56

P1819 TRANSFER CONTROL DEVICEDLN-51
< COMPONENT DIAGNOSIS > [ATX14B]
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With CONSULT-III
1. Turn ignition switch ON. (Do not start engine.)
2. Select SELF-DIAG RESULTS mode for ALL MODE AWD/4WD with CONSULT-III.
3. Touch ERASE.
4. Turn ignition switch OFF and wait at least 10 seconds.
5. Perform the self-diagnosis again.
Is the SHIFT ACT CIR [P1819] displayed?
YES >> Replace transfer control unit. Refer to DLN-128, "Removal and Installation".
NO >> Inspection End.
8.PERFORM SELF-DIAGNOSIS (WITHOUT CONSULT-III)
Without CONSULT-III
1. Perform the self-diagnosis and then eras e self-diagnostic results. Refer to DLN-18, "CONSULT-III Func-
tion (ALL MODE AWD/4WD)".
2. Perform the self-diagnosis again.
Do the self-diagnostic results indicate transfer control device?
YES >> Replace transfer control unit.
NO >> Inspection End.
Revision: March 2010 2008 QX56

DLN-100
< SYMPTOM DIAGNOSIS >[ATX14B]
4WD SYSTEM SYMPTOMS
SYMPTOM DIAGNOSIS
4WD SYSTEM SYMPTOMS
Symptom TableINFOID:0000000001737182
If 4WD warning lamp turns ON, perform self-diagnosis. Refer to DLN-18, "CONSULT-III Function (ALL MODE AWD/4WD)".
NOTE:
• Light tight-corner braking symptom may occur depending on driving conditions in AUTO mode. This is not a
malfunction.
• Heavy tight-corner braking symptom occurs when vehicle is driven in the following conditions: 4WD shift
switch is 4H or 4LO, steering wheel is turned fully to either side.
Symptom ConditionReference page
4WD shift indicator lamp and 4LO indicator lamp do not turn ON
(4WD shift indicator lamp and 4LO indicator lamp check) Ignition switch: ON
DLN-101
4WD warning lamp does not turn ON
(4WD warning lamp check) Ignition switch: ON
DLN-103
4WD shift indicator lamp or 4LO indicator lamp does not change Engine runningDLN-105
ATP warning lamp does not turn ON Engine runningDLN-107
4WD shift indicator lamp keeps flashing Engine runningDLN-109
4WD warning lamp flashes rapidly (2 times/second) While drivingDLN-110
4WD warning lamp flashes slowly
(1 time/2 seconds) While driving
DLN-111
Heavy tight-corner braking symptom occurs
(See NOTE.) • While driving
•AUTO mode
• Steering wheel is turned fully
to either side DLN-112
ATP switch does not operate
Engine runningDLN-114
4WD system does not operate While drivingDLN-116
Revision: March 2010 2008 QX56

ATP WARNING LAMP DOES NOT TURN ONDLN-107
< SYMPTOM DIAGNOSIS > [ATX14B]
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ATP WARNING LAMP DOES NOT TURN ON
DescriptionINFOID:0000000001737189
ATP warning lamp does not turn ON when the transfer case is switched in or out of 4LO with the A/T selector
lever in N position.
Diagnosis ProcedureINFOID:0000000001737190
1.CHECK SYSTEM FOR CAN COMMUNICATION LINE
Perform self-diagnosis. Refer to DLN-18, "
CONSULT-III Function (ALL MODE AWD/4WD)".
Do the self-diagnostic results indicate CAN communication?
YES >> Perform trouble diagnosis for CAN communication line.
NO >> GO TO 2.
2.CHECK SYSTEM FOR 4WD SHIFT SWITCH
Perform trouble diagnosis for 4WD shift switch system. Refer to DLN-31, "
Diagnosis Procedure".
Are the inspection results normal?
YES >> GO TO 3.
NO >> Repair or replace damaged parts.
3.CHECK SYSTEM FOR TRANSMIS SION RANGE SWITCH SIGNAL
Perform trouble diagnosis for transmission range switch signal system. Refer to DLN-38, "
Diagnosis Proce-
dure".
Are the inspection results normal?
YES >> GO TO 4.
NO >> Repair or replace damaged parts.
4.CHECK SYSTEM FOR ATP SWITCH
Perform trouble diagnosis for ATP switch system. Refer to DLN-114, "
Diagnosis Procedure".
Are the inspection results normal?
YES >> GO TO 5.
NO >> Repair or replace damaged parts.
5.CHECK HARNESS BETWEEN TR ANSFER CONTROL UNIT AND COMBINATION METER
1. Turn ignition switch OFF. (Stay for at least 5 seconds.)
2. Disconnect transfer control unit harness connector and combination meter harness connector.
3. Check continuity between the following terminals.
- Transfer control unit harness connector E142 (B) terminal 15 and combination meter harness connector M23 (A) terminal 43.
Continuity should exist.
AWDIA0185ZZ
Revision: March 2010 2008 QX56

DLN-114
< SYMPTOM DIAGNOSIS >[ATX14B]
ATP SWITCH
ATP SWITCH
DescriptionINFOID:0000000001737199
The ATP indicator is ON when the transfer case is not in neutral.
Diagnosis ProcedureINFOID:0000000001737200
DIAGNOSTIC PROCEDURE
1.CHECK ATP SWITCH SIGNAL

With CONSULT-III
1. Start engine.
2. Select DATA MONITOR mode for ALL MODE AWD/4WD with CONSULT-III.
3. Read out the value of ATP SWITCH.
Without CONSULT-III
1. Start engine.
2. Check voltage between transfer control unit harness connector
terminal and ground.
Are inspection results normal?
YES >> GO TO 5.
NO >> GO TO 2.
2.CHECK HARNESS BETWEEN TRANSFER CONTROL UNIT AND ATP SWITCH
1. Turn ignition switch OFF. (Stay for at least 5 seconds.)
2. Disconnect transfer control unit harness connector and the ATP switch harness connector.
3. Check continuity between transfer control unit harness connec- tor E143 terminal 40 and ATP switch harness connector F55 ter-
minal 8.
Also check harness for short to ground and short to power.
Are inspection results normal?
YES >> GO TO 3.
NO >> Repair or replace damaged parts.
3.CHECK GROUND CIRCUIT
Condition Display value
• Vehicle stopped
• Engine running
• A/T selector lever N
• Brake pedal de- pressed 4WD shift switch
: 4H to 4LO or 4LO to 4H
(While actuator motor is operating.)
ON
Except the above OFF
Connector TerminalConditionVoltage
(Approx.)
E143 40 -
Ground • Vehicle stopped
• Engine running
• A/T selector lever
N
• Brake pedal de- pressed 4WD shift switch: 4H
to 4LO or 4LO to 4H
(While actuator motor
is operating.)
0V
Except the above Battery
voltage
SDIA2755E
Continuity should exist.
SDIA2756E
Revision: March 2010
2008 QX56

DLN-118
< PRECAUTION >[ATX14B]
PRECAUTIONS
PRECAUTION
PRECAUTIONS
Precaution for Supplemental Restraint Syst
em (SRS) "AIR BAG" and "SEAT BELT
PRE-TENSIONER"
INFOID:0000000004857590
The Supplemental Restraint System such as “A IR 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 w hether the front occupants are belted or unbelted.
Information necessary to service the system safely is included in the SR and SB section of this Service Man-
ual.
WARNING:
• To avoid rendering the SRS inopera tive, 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 performed by
an authorized NISSAN/INFINITI dealer.
• Improper maintenance, including in correct removal and installation of the SRS, can lead to personal
injury caused by unintent ional activation of the system. For re moval of Spiral Cable and Air Bag
Module, see the SR section.
• Do not use electrical test equipmen t on any circuit related to the SRS unless instructed to in this
Service Manual. SRS wiring harn esses can be identified by yellow and/or orange harnesses or har-
ness connectors.
PRECAUTIONS WHEN USING POWER TOOLS (AIR OR ELECTRIC) AND HAMMERS
WARNING:
• When working near the Airbag Diagnosis Sensor Unit or other Airbag System sensors with the Igni-
tion ON or engine running, DO NOT use air or electri c power tools or strike near the sensor(s) with a
hammer. Heavy vibration could activate the sensor( s) and deploy the air bag(s), possibly causing
serious injury.
• When using air or electric power tools or hammers , always switch the Ignition OFF, disconnect the
battery, and wait at least 3 minu tes before performing any service.
Precaution Necessary for Steering W heel Rotation After Battery Disconnect
INFOID:0000000004857589
NOTE:
• This Procedure is applied only to models with Intelligent Key system and NATS (NISSAN ANTI-THEFT SYS-
TEM).
• Remove and install all control units after disconnecting both battery cables with the ignition knob in the
″LOCK ″ position.
• Always use CONSULT-III to perform self-diagnosis as a part of each function inspection after finishing work.
If DTC is detected, perform trouble diagnosis according to self-diagnostic results.
For models equipped with the Intelligent Key system and NATS, an electrically controlled steering lock mech-
anism is adopted on the key cylinder.
For this reason, if the battery is disconnected or if the battery is discharged, the steering wheel will lock and
steering wheel rotation will become impossible.
If steering wheel rotation is required when battery pow er is interrupted, follow the procedure below before
starting the repair operation.
OPERATION PROCEDURE
1. Connect both battery cables. NOTE:
Supply power using jumper cables if battery is discharged.
2. Use the Intelligent Key or mechanical key to turn the ignition switch to the ″ACC ″ position. At this time, the
steering lock will be released.
3. Disconnect both battery cables. The steering lock will remain released and the steering wheel can be rotated.
4. Perform the necessary repair operation.
Revision: March 2010 2008 QX56