2009 INFINITI QX56 Factory Service Manual

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Page 1065 of 4171

INFINITI QX56 2009 Factory Service Manual
DIAGNOSIS AND REPAIR WORKFLOWDLN-9
< BASIC INSPECTION > [ATX14B]
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DLN
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O P
Flash rapidly>>Refer to DLN-112, "Diagnosis Procedure".
Flash slowly>>Refer to DLN-113, "Diagnosis

Page 1066 of 4171

INFINITI QX56 2009 Factory Service Manual
DLN-10
< FUNCTION DIAGNOSIS >[ATX14B]
4WD SYSTEM
FUNCTION DIAGNOSIS
4WD SYSTEM
System DiagramINFOID:0000000003772075
COMPONENT DESCRIPTION
WDIA0164E
Components Function
Transfer control unit Controls

Page 1067 of 4171

INFINITI QX56 2009 Factory Service Manual
4WD SYSTEMDLN-11
< FUNCTION DIAGNOSIS > [ATX14B]
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DLN
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O PSystem DescriptionINFOID:0000000003772076
CONTROL SYSTEM
ABS actuator and electric unit
(control unit) Transmits vehi

Page 1068 of 4171

INFINITI QX56 2009 Factory Service Manual
DLN-12
< FUNCTION DIAGNOSIS >[ATX14B]
4WD SYSTEM
ALL-MODE 4WD Transfer Basic Control
SDIA3396E
Revision: December 20092009 QX56

Page 1069 of 4171

INFINITI QX56 2009 Factory Service Manual
4WD SYSTEMDLN-13
< FUNCTION DIAGNOSIS > [ATX14B]
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Hydraulic Control Circuits
TRANSFER CONTROL UNIT
Transfer control unit controls transfer control dev
ice and it dir

Page 1070 of 4171

INFINITI QX56 2009 Factory Service Manual
DLN-14
< FUNCTION DIAGNOSIS >[ATX14B]
4WD SYSTEM
Displays 4LO condition while engine is running. 4LO indi
cator lamp flashes if transfer gear does not shift
completely under 2WD, AUTO, 4H ⇔4LO. (

DLN-14
< FUNCTION DIAGNOSIS >[ATX14B]
4WD SYSTEM
Displays 4LO condition while engine is running. 4LO indi
cator lamp flashes if transfer gear does not shift
completely under 2WD, AUTO, 4H ⇔4LO. (When 4WD warning lamp is turned on, 4LO indicator lamp is
turned off.)
Turns ON for approximately 1 second when ignition switch is turned ON, for purpose of lamp check.
4WD WARNING LAMP
Turns on or flashes when there is a malfunction in 4WD system.
Also turns on when ignition switch is turned ON, for purpose of lamp che\
ck. Turns OFF approximately 1 sec-
ond after the engine starts if system is normal.
4WD Warning Lamp Indication
ATP WARNING LAMP
When the A/T selector lever is in P position, the vehicle may move if the transfer case is in neutral. ATP warn-
ing lamp is turned on to indicate this condition to the driver.
LINE PRESSURE SWITCH
With the transfer system design, cont rol of the oil pressure provides the transmission of drive torque to the
front wheels. The main pressure to control the oil pressure is referred to as the line pressure.
The line pressure switch determines whether or not adequate line pressure has built up under different oper-
ating conditions.
The line pressure switch closes when line pressure is produced.
The line pressure switch senses line pressure abnormalities and turns the 4WD warning lamp ON.
CLUTCH PRESSURE SWITCH
The clutch pressure switch determines whether or not adequate clutch pressure has built up under different
operating conditions.
The clutch pressure switch closes when clutch pressure is produced.
The clutch pressure switch senses clutch pressu re abnormalities and turns the 4WD warning lamp ON.
WAIT DETECTION SWITCH
The wait detection switch operates when there is circulating torque produced in the propeller shaft (L→H) or
when there is a phase difference between 2-4 sleeve and clutch drum (H →L). After the release of the circu-
lating torque, the wait detection switch helps provi de the 4WD lock gear (clutch drum) shifts. A difference
may occur between the operation of the 4WD shift swit ch and actual drive mode. At this point, the wait
detection switch senses an actual drive mode.
The wait detection switch operates as follows.
- 4WD lock gear (clutch drum) locked: ON
- 4WD lock gear (clutch drum) released: OFF
The wait detection switch senses an actual drive mode and the 4WD shift indicator lamp indicates the vehi-
cle drive mode.
ATP SWITCH
ATP switch detects if transfer case is in neutral by the position of the L-H shift fork.
NOTE:
Transfer case may be in neutral when shifting between 4H-4LO.
NEUTRAL-4LO SWITCH
The neutral-4LO switch detects that tr ansfer gear is in neutral or 4LO (or shifting from neutral to 4LO) condi-
tion by L-H shift fork position.
Condition 4WD warning lamp
System normal OFF
Lamp check Turns ON when ignition switch is turned ON.
Turns OFF after engine start.
4WD system malfunction ON
During self-diagnosis Flashes malfunction mode.
Large difference in diameter of front/
rear tires Flashes slow (1 flash / 2 seconds)
(Continues to flash until the ignition switch is turned OFF)
High fluid temperature in transfer case Flashes rapidly (2 flashes / 1 second)
(Continues to flash until fluid temperature returns to normal)
Revision: December 20092009 QX56

Page 1071 of 4171

INFINITI QX56 2009 Factory Service Manual
4WD SYSTEMDLN-15
< FUNCTION DIAGNOSIS > [ATX14B]
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DLN
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TRANSFER FLUID TEMPERATURE SENSOR
The transfer fluid temperature sensor detects the trans fer fluid temperature and s

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 trans mitted 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 0
0 - 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: December 20092009 QX56

Page 1072 of 4171

INFINITI QX56 2009 Factory Service Manual
DLN-16
< FUNCTION DIAGNOSIS >[ATX14B]
4WD SYSTEM
Actuator Motor
Moves shift rods when signaled by transfer control unit.
Actuator Position Switch
Detects actuator motor position and then sends signal

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