INFINITI QX56 2010 Factory Service Manual

DIAGNOSIS AND REPAIR WORKFLOWDLN-9
< BASIC INSPECTION > [ATX14B]
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Flash rapidly>>Refer to DLN-112, "Diagnosis Procedure".
Flash slowly>>Refer to DLN-113, "
Diagnosis Procedure".
NO >> GO TO 2.
2.CHECK TIGHT CORNER BRAKING SYMPTOM (1)
1. Set 4WD shift switch to AUTO position.
2. Drive vehicle at speed lower than 20 km/h (12 MPH) with steering wheel fully turned.
Does tight corner braking symptom occur?
YES >> GO TO DLN-114, "Diagnosis Procedure".
NO >> GO TO 3.
3.CHECK TIGHT CORNER BRAKING SYMPTOM (2)
1. Set 4WD shift switch to 4HI position.
2. Drive vehicle at speed lower than 20 km/h (12 MPH) with steering wheel fully turned.
Does tight corner braking symptom occur?
YES >> Inspection End.
NO >> GO TO DLN-118, "
Diagnosis Procedure".
Revision: April 20092010 QX56

DLN-10
< FUNCTION DIAGNOSIS >[ATX14B]
4WD SYSTEM
FUNCTION DIAGNOSIS
4WD SYSTEM
System DiagramINFOID:0000000005148770
COMPONENT DESCRIPTION
WDIA0164E
Components
Function
Transfer control unit Controls transfer control device, control valves and shifts between 2WD/4WD and 4H/4LO.
Transfer control device Integrates actuator motor and actuator position switch.
2-4WD shift solenoid valve Controls oil pressure and allows shifting between 2WD and 4WD.
Clutch pressure solenoid valve Controls oil pressure and distributes torque between front and rear tires.
Line pressure switch Detects line pressure.
Clutch pressure switch Detects clutch pressure.
Transfer fluid temperature sensor Detects transfer fluid temperature.
Actuator motor Moves shift rods when signaled by transfer control unit.
Actuator position switch Detects actuator motor position.
Wait detection switch Detects whether or not 4WD lock gear is locked.
4LO switch Detects if transfer case is in 4LO.
ATP switch Detects if transfer case is in neutral.
4WD shift switch Allows driver to select from 2WD/4WD, 4H/4LO and AUTO.
4WD warning lamp • Illuminates if malfunction is detected in 4WD system.
• Flashes (1 flash / 2 seconds) if large difference in diameter of front and rear tires.
• Flashes (2 flashes / 1 second) if high transfer fluid temperature is detected.
AT P w a r n i n g l a m p Indicates that A/T parking mechanism does not operate when A/T selector lever is in P position
because transfer case is in neutral.
4WD shift indicator lamp Displays driving range selected by 4WD shift switch.
4LO indicator lamp Displays 4LO range.
Revision: April 20092010 QX56

4WD SYSTEMDLN-11
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O PSystem DescriptionINFOID:0000000005148771
CONTROL SYSTEM
ABS actuator and electric unit
(control unit) Transmits vehicle speed signal via CAN communication to transfer control unit.
TCM Transmits the following signal via CAN communication to transfer control unit.
• Output shaft revolution signal
• A/T position indicator signal (transmission range switch signal)
ECM Transmits the following signals via CAN communication to transfer control unit.
• Engine speed signal
• Accelerator pedal position signal
Components
Function
Revision: April 20092010 QX56

DLN-12
< FUNCTION DIAGNOSIS >[ATX14B]
4WD SYSTEM
ALL-MODE 4WD Transfer Basic Control
SDIA3396E
Revision: April 20092010 QX56

4WD SYSTEMDLN-13
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Hydraulic Control Circuits
TRANSFER CONTROL UNIT
• Transfer control unit controls transfer control dev
ice and it directs shifts from 4H-4LO and 2WD-4WD.
• Self-diagnosis can be done.
TRANSFER SHIFT HIGH AND LOW RELAYS
Transfer shift high and low relays apply power supply to transfer control device (actuator motor).
TRANSFER SHUT OFF RELAY
Transfer shut off relay applies power supply to transfer motor relay.
4WD SHIFT SWITCH AND INDICATOR LAMPS
4WD Shift Switch
Able to select from 2WD, AUTO, 4H or 4LO.
4WD Shift Indicator Lamp
• Displays driving conditions selected by 4WD shift switch with 2WD, AUTO and 4H indicators while engine is running. (When 4WD warning lamp is turned on, all 4WD shift indicator lamps are turned off.)
• Turns ON for approximately 1 second when ignition switch is turned ON, for purpose of lamp check.
4LO Indicator Lamp
LDIA0055E
WDIA0163E
Revision: April 20092010 QX56

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: April 20092010 QX56

4WD SYSTEMDLN-15
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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: April 20092010 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:0000000005148772
AWDIA0549ZZ
Revision: April 20092010 QX56

4WD SYSTEMDLN-17
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CAN CommunicationINFOID:0000000005148773
Refer to LAN-14, "Trouble Diagnosis Flow Chart".
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. A: Transfer dropping resistor E135
B: Transfer motor relay E153, E154
(View with battery removed)
Revision: April 20092010 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:0000000005148774
FUNCTION
CONSULT-III can display each diagnostic item us ing the diagnostic test modes shown following.
SELF DIAGNOSTIC 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-97, "
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.
Diagnostic Mode Description
Self Diagnostic Result 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 Monitor The results of transmit/receive diagnosis of CAN communication can be read. ECU Identification Transfer control unit part number can be read.
Revision: April 20092010 QX56