2004 INFINITI QX56 transfer motor

TF-10
ALL-MODE 4WD SYSTEM
Revision: August 20072004 QX56
ALL-MODE 4WD SYSTEMPFP:00000
Cross-sectional ViewEDS0017N
LDIA0053E
1. Center case 2. Chain 3. Multiple disc clutch
4. Rear case 5. Main shaft 6. Clutch hub assembly
7. Sub oil pump 8. Transfer motor 9. Control valve
10. Front drive shaft 11. Drain plug 12. 2-4 sleeve
13. Sun gear assembly 14. L-H sleeve 15. Planetary carrier assembly
16. Internal gear 17. Front case

ALL-MODE 4WD SYSTEM
TF-15
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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
TF-29
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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. —

TF-32
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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Revision: August 20072004 QX56
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

TF-36
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
Revision: August 20072004 QX56
N position switch TF [ON-OFF] N position switch of transfer
Line pressure switch [ON-OFF] Line pressure switch
Clutch pressure switch [ON-OFF] Clutch pressure switch
ATP switch [ON-OFF]—
N position switch AT [ON-OFF] “N” position on A/T PNP switch
R position switch AT [ON-OFF] “R” position on A/T PNP switch
P position switch AT [ON-OFF] “P” position on A/T PNP switch
ABS operation switch [ON-OFF] ABS operation switch
Wait detection switch [ON-OFF] —
Throttle positionThrottle opening recognized by transfer
control unit
4WD-mode4WD-mode recognized by transfer control
unit (2WD, AUTO, 4H & 4LO)
Vehicle speed comp [km/h (MPH)]Vehicle speed recognized by transfer con-
trol unit
*Control torque [N·m (kg-m, ft.-lb.)]Calculated torque recognized by transfer
control unit
Duty solenoid valve [%]
(Transfer 4WD solenoid valve)—
2-4WD shift solenoid valve [ON-
OFF]
Control signal outputs of transfer control
unit Transfer motor relay [ON-OFF]
Shift activating 1 [ON-OFF]
Shift activating 2 [ON-OFF]
2-4WD shift solenoid valve monitor
[ON-OFF]
Check signal (re-input signal) of transfer
control unit control signal output is dis-
played. If circuit is shorted or open, ON/OFF
state does not change. Transfer motor relay monitor [ON-
OFF]
Shift activating monitor 1 [ON-OFF]
Shift activating monitor 2 [ON-OFF]
4WD fail lamp [ON-OFF]Transfer control unit control signal output for
4WD warning lamp (left)
Shift position switch 1 [ON-OFF] —
Shift position switch 2 [ON-OFF] —
2WD indicator lamp [ON-OFF]Transfer control unit control signal output for
4WD shift indicator lamp (rear)
AUTO indicator lamp [ON-OFF]Transfer control unit control signal output for
4WD shift indicator lamp (front & rear)
LOCK indicator lamp [ON-OFF]Transfer control unit control signal output for
4WD shift indicator lamp (center)
4LO indicator lamp [ON-OFF]Transfer control unit control signal output for
4WD shift indicator lamp (right) Item [Unit]Monitor item
Remarks ECU
INPUT
SIGNALSMAIN
SIGNALSSELEC-
TION
FROM
MENU

TF-38
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
Revision: August 20072004 QX56
REFERENCE VALUE IN DATA MONITOR MODE
Indicated items
(Screen terms for CONSULT-II, “DATA
MONITOR” mode)Display Conditions
Throttle position sensor
(THRTL POS SEN) 0.0/8 - 8.0/8 Throttle valve fully closed to fully open
Transfer fluid temperature sensor
(FLUID TEMP SE)Approx. 1.5 - 0.5V Transfer fluid temperature approx. 20 - 80°C (68 - 176°F)
ABS operation switch
(ABS OPER SW)OFF ABS is not operating.
ON ABS is operating.
2WD position
(2WD SWITCH)ON 4WD shift switch is in “2WD”.
OFF Except the above condition
Lock position
(LOCK SWITCH)ON 4WD shift switch is in “4H”.
OFF Except the above condition
Neutral-4LO switch
(N POSI SW TF)
AT P s w i tc h
(ATP SWITCH)
Wait detection switch
(WAIT DETCT SW)4WD shift switch position2WD,
AUTO, 4H(N) 4LO
AT P s w i t c h O F F O N O F F
Neutral-4LO switch/Wait detec-
tion switch See Note.OFF ON
Note: When shifting into or out of “4LO” the switches turn ON when “Wait” function is oper-
ating and they turn OFF when “Wait” function is canceled.
Tran s fe r mo to r re lay
(MOTOR RELAY)
Transfer motor relay monitor
(MOTOR RELAY MON)Throttle valve4WD
shift
switchA/T selector
leverMotor relay/
Motor relay
monRemarks
Fully closed2WD — OFF —
AUTO,
4LOP, N O F F
ON for approx. 2 sec. after
shifting to “P” and “N”
Others ON
4HPOFF
ON for approx. 2 sec. after
shifting to “P”
Others ON
Line pressure switch
(LINE PRES SW)OFFThe vehicle has been left at room temperature for 5 min-
utes and more with ignition switch in “OFF” position.
ONIgnition switch in “ON”, and 4WD shift switch in “AUTO” or
“4H” and A/T selector lever in “D”.
Clutch pressure switch
(CL PRES SW)OFFIgnition switch in “ON”, and 4WD shift switch in “2WD”.
(“Wait” function is not operating.)
ONIgnition switch in “ON”, and 4WD shift switch in “AUTO” or
“4H” and A/T selector lever in “D”. (“Wait” function is not
operating.)
Vehicle speed
(VHCL/S COMP)0 km/h (0 MPH) — —
Control torque
(COMP CL TORQ)0 kg-m
4WD shift switch
(“Wait” function is not oper-
ating.)In “2WD” position
39 - 1,353 N·m
(4 - 138 kg-m, 29 - 998 ft.-lb.)In “AUTO” position
1,353 N·m
(138 kg-m, 998 ft.-lb.)In “4H” or “4LO” position
4WD solenoid
(DUTY SOLENOID)4% In “2WD” position
96 - 4% In “AUTO” position
4% In “4H” or “4LO” position

TF-56
TROUBLE DIAGNOSIS — GENERAL DESCRIPTION
Revision: August 20072004 QX56
114WD shift indicator lamp
(4H)“4H” indicator lamp comes ON. Less than 1V
4WD shift switch is set to any posi-
tion other than 4H.Battery voltage
124WD shift indicator lamp
(4LO)“4LO” indicator lamp comes ON. 0V
4WD shift switch is set to any posi-
tion other than 4LO.Battery voltage
13 Transfer shift relay (Low)
&While actuator is operating (4LO →
4H)Battery voltage
Actuator does not operate. 0V
14 Transfer motor relayTransfer motor relay is ON. Battery voltage
Transfer motor relay is OFF. Less than 1V
15 ATP lampAT selector lever is set to P position. Battery voltage
AT selector lever is set to any posi-
tion other than P.0V
16 Power supply —Ignition key is set to ON position. Battery voltage
Ignition key is set to OFF position. 0V
18 4WD shift switch (4H)
&4WD shift switch is set to 4H posi-
tion.Battery voltage
4WD shift switch is set to any posi-
tion other than 4H.Less than 1V
19 4WD solenoid valve4WD shift switch is set to AUTO posi-
tion.1.5 - 3V
4WD shift switch is set to any posi-
tion other than 2WD.Less than 1V
214WD shift indicator lamp
(AUTO)“AUTO” indicator lamp comes ON. 0V
4WD shift switch is set to any posi-
tion other than AUTO.Battery voltage
22 Power supply —Ignition key is set to ON position. Battery voltage
Ignition key is set to OFF position. 0V
23 4WD shift switch (4LO)
&4WD shift switch is set to 4LO posi-
tion.Battery voltage
4WD shift switch is set to any posi-
tion other than 4LO.Less than 1V
24 4WD shift switch (AUTO)4WD shift switch is set to AUTO posi-
tion.Battery voltage
4WD shift switch is set to any posi-
tion other than AUTO.Less than 1V
25 Neutral-4LO switchTransfer is set to 4LO position. 0V
Transfer is set to any position other
than 4LO.Battery voltage
27Transfer 4H actuator
switch4WD shift switch is set to 4H posi-
tion.Less than 1V
4WD shift switch is set to any posi-
tion other than 4H.Battery voltage
28 Sensor ground — Less than 1V Te r m i n a l
No.Item ConditionJudgement standard
(Approx.)