2008 INFINITI QX56 4WD

DLN-14
< FUNCTION DIAGNOSIS >[ATX14B]
4WD SYSTEM
• Displays 4LO condition while engine is running. 4LO indicator 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, control 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 pressure 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 transfer 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: March 2010 2008 QX56

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-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 to transfer control unit.
Component Parts LocationINFOID:0000000001737098
AWDIA0549ZZ
Revision: March 2010
2008 QX56

4WD SYSTEMDLN-17
< FUNCTION DIAGNOSIS > [ATX14B]
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CAN CommunicationINFOID:0000000001737099
Refer to LAN-51, "DTC Index".
1. A: Transfer shut off relay E69
B: Transfer shift low relay E47
C: Transfer shift high relay E46 2. A: Actuator
B: Transfer control device F58
C: Actuator lever
D: Transfer case 3. Wait detection switch F59
(View with transfer case removed)
4. A: Clutch pressure switch B: Line pressure switch
C: Transfer fluid temperature sensor
D: 2-4WD shift solenoid valve
E: Clutch pressure solenoid valve
(View with contro l valve removed
from transfer case) 5. A: Neutral 4LO switch F60
B: ATP switch F55
C: Transfer motor F57
D: Transfer terminal cord assembly F56
E: Oil filter 6. Combination meter M23, M24
A: 4WD warning lamp
B: ATP warning lamp
C: 4LO indicator lamp (located in in-
formation display)
D: 4WD shift indicator lamp
7. 4WD shift switch M141 8. Transfer control unit E142, E143 9. Transfer dropping resistor E135
Transfer motor relay E153, E154
(View with battery removed)
Revision: March 2010 2008 QX56

DLN-18
< FUNCTION DIAGNOSIS >[ATX14B]
DIAGNOSIS SYSTEM (T
RANSFER CONTROL UNIT)
DIAGNOSIS SYSTEM (TRA NSFER CONTROL UNIT)
CONSULT-III Function (ALL MODE AWD/4WD)INFOID:0000000001737100
FUNCTION
CONSULT-III can display each diagnostic item us ing the diagnostic test modes shown following.
SELF-DIAG RESULT MODE
Operation Procedure
1. Connect CONSULT-III.
2. With engine at idle, touch SELF-DIAG RESULTS.
Display shows malfunction experienced since the last erasing operation.
NOTE:
The details for TIME are as follows:
• 0: Error currently detected with transfer control unit.
• Except for 0: Error detected in the pa st and memorized with transfer control unit.
Detects frequency of driving after DTC occurs (frequency of turning ignition switch ON/OFF).
How to Erase Self-d iagnostic Results
1. Perform applicable inspection of malfunctioning item and then repair or replace.
2. Start engine and select SELF-DIAG RESULTS m ode for ALL MODE AWD/4WD with CONSULT-III.
3. Touch ERASE on CONSULT-III screen to erase DTC memory. CAUTION:
If memory cannot be erased, pe rform applicable diagnosis.
SELF-DIAGNOSTIC PROCEDURE (WITHOUT CONSULT-III)
Description
If the engine starts when there is a malfunction in the 4WD system, the 4WD warning lamp turns ON or flickers
in the combination meter. When the system functions properly, the warning lamp turns ON when the ignition
switch is turned to ON, and it turns OFF after engine starts . To locate the cause of a malfunction, start the self-
diagnosis function. The 4WD warning lamp in the combination meter will indicate the malfunction area by
flashing according to the self-diagnostic results. Refer to DLN-95, "
DTC Index".
Diagnostic Procedure
1. Warn up engine.
2. Move A/T selector lever to P position.
3. Turn 4WD shift switch to 2WD position.
4. Turn ignition switch ON and OFF at least twice, and then turn ignition switch OFF.
5. Turn 4WD shift switch to AUTO position.
6. Turn ignition switch ON. (Do not start engine.)
7. 4WD warning lamp ON.
8. Move A/T selector lever to R position.
9. Turn 4WD shift switch to 2WD, AUTO and 2WD in order.
10. Move A/T selector lever to D position.
11. Turn 4WD shift switch to 4H, AUTO and 4H in order.
ALL MODE AWD/4WD diagnostic mode Description
SELF-DIAG RESULTS Displays transfer control unit self-diagnosis results. DATA MONITOR Displays transfer control unit input/output data in real time.
WORK SUPPORT Supports inspections and adjustments. Commands are transmitted to the transfer control
unit for setting the status suitable for required operation, input/output signals are received
from the transfer control unit and received data is displayed.
CAN DIAG SUPPORT MNTR The results of transmit/receive diagnosis of CAN communication can be read. ECU PART NUMBER Transfer control unit part number can be read.
Revision: March 2010 2008 QX56

DIAGNOSIS SYSTEM (TRANSFER CONTROL UNIT)DLN-19
< FUNCTION DIAGNOSIS > [ATX14B]
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12. Move A/T selector lever to N position.
13. Turn 4WD shift switch to AUTO position.
14. Move A/T selector lever to P position.
15. Read the flickering of 4WD warning lamp.
Self-diagnosis example
ERASE SELF-DIAGNOSIS
• In order to make it easier to find the cause of hard-to-duplicate malfunctions, malfunction information is
stored into the control unit as necessary during use by the user. This memory is not erased no matter how
many times the ignition switch is turned ON and OFF.
• However, this information is erased by turning igni tion switch OFF after performing self-diagnostics or by
erasing the memory using the CONSULT-III.
DATA MONITOR MODE
Operation Procedure
1. Connect CONSULT-III.
2. Touch DATA MONITOR.
3. Select from SELECT MONITOR ITEM, screen of data monitor mode is displayed.
NOTE:
When malfunction is detected, CONSUL T-III performs REAL-TIME DIAGNOSIS.
Also, any malfunction detected while in th is mode will be displayed at real time.
Display Item List
×: Standard –: Not applicable
PDIA0227E
Monitored item (Unit) Monitor item selection
Remarks
ECU INPUT
SIGNALS MAIN
SIGNALS SELEC-
TION FROM MENU
VHCL/S SEN·FR [km/h] or [mph] ×–×Wheel speed calculated by ABS actuator and
electric unit (control unit).
Signal input with CAN communication line.
VHCL/S SEN·RR [km/h] or [mph] ×–×Wheel speed calculated by TCM.
Signal input with CAN communication line.
ENGINE SPEED [rpm] ×–×Engine speed calculated by ECM.
Signal input with CAN communication line.
THRTL POS SEN [V] ×–×Accelerator peda
l position (APP) sensor sig-
nal voltage is displayed.
Signal input with CAN communication line.
FLUID TEMP SE [V] ×–×Transfer fluid temperature sensor signal volt-
age is displayed.
BATTERY VOLT [V] ×–×Power supply voltage for transfer control unit.
2WD SWITCH [ON/OFF] ×–×4WD shift switch status is displayed.
AUTO SWITCH [ON/OFF] ×–×4WD shift switch status is displayed.
LOCK SWITCH [ON/OFF] ×–×4WD shift switch status is displayed.
(LOCK means 4H of 4WD shift switch.)
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

DIAGNOSIS SYSTEM (TRANSFER CONTROL UNIT)DLN-21
< FUNCTION DIAGNOSIS > [ATX14B]
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WORK SUPPORT
When there is no malfunction with transfer and 4WD sys tem, the following symptoms in AUTO mode may be
claimed by a customer: vibration when accelerating on a low µ road (snow-covered or icy road) or a slight
shock is felt at a few hertz as if it were being pushed lightly from behind.
It is possible to deal with these symptoms by changing the CLUTCH FORCE RELEASE LIMIT VALUE. How-
ever, be careful when changing the value because it may adversely affect driving performance.
Operation Procedure
1. Connect CONSULT-III.
2. Touch WORK SUPPORT.
3. Select from CLUTCH/F RLS LIM ADJ, screen of data monitor mode is displayed.
Clutch Force Release Limit Adjustment
1. Initial CLUTCH FORCE RELEASE LIMIT value 0.3 kgm appears under CONDITION SETTING on CON-
SULT-III display.
2. Touch 1.2 on the display.
3. Display changes to NOW ADJUSTING in a short time.
4. When clutch force release limit value is set to 1.2 kgm, current value 0.3 kgm shown on display will be replaced by 1.2 kgm and ADJUSTME NT COMPLETE will appear at the same time. Clutch force release
limit value setting is now complete.
ATP IND [ON/OFF] ––×Control status of ATP warning lamp is dis-
played.
SHIFT POS SW1 [ON/OFF] ×–×Actuator position switch 1 (Low) signal status
is displayed.
SHIFT POS SW2 [ON/OFF] ×–×Actuator position switch 2 (high) signal status
is displayed.
SHIFT ACT1 [ON/OFF] –×× Output condition to actuator motor (clockwise)
SHIFT AC MON1 [ON/OFF] ×–×Check signal for transfer control unit signal
output
SHIFT ACT2 [ON/OFF] –×× Output condition to actuator motor (counter-
clockwise)
SHIFT AC MON2 [ON/OFF] ×–×Check signal for transfer control unit signal
output
T/F F SPEED [km/h] or [mph] ×–×Displayed, but do not use.
A/T R SPEED [km/h] or [mph] ×–×Output speed sensor signal calculated by
TCM.
Signal input with CAN communication line.
AT GEAR POSI [1/2/3/4/5] ×–×A/T actual gear position is displayed.
Monitored item (Unit)
Monitor item selection
Remarks
ECU INPUT
SIGNALS MAIN
SIGNALS SELEC-
TION FROM
MENU
1.2 kg-m : Tight corner braking symptom is alleviated. However, vibration may occur when acceler-
ating on a low µ road (icy road, etc.).
0.3 kg-m : Initial set value.
0.2 kg-m : Do not set to th is value because the tight
corner braking symptom will get worse.
Revision: March 2010 2008 QX56