2009 INFINITI QX56 ECU

DLN-98
< ECU DIAGNOSIS >[ATX14B]
TRANSFER CONTROL UNIT
DTC CONSULT-III Diagnostic item is detected when... Reference
[P1802] CONTROL UNIT 1 Malfunction is detected in the memory (RAM) sys-
tem of transfer control unit.
Refer to DLN-24
.
[P1803] CONTROL UNIT 2 Malfunction is detected in the memory (ROM) sys-
tem of transfer control unit.
[P1804] CONTROL UNIT 3 Malfunction is detected
in the memory (EEPROM)
system of transfer control unit.
[P1807] VHCL SPEED SEN·AT  Malfunction is detected in output shaft revolution
signal that is output from TCM through CAN com-
munication.
 Improper signal is input while driving. Refer to
DLN-26
.
[P1808] VHCL SPEED SEN·ABS  Malfunction is detected in vehicle speed signal
that is output from ABS actuator and electric unit
(control unit) through CAN communication.
 Improper signal is input while driving. Refer to
DLN-27
.
[P1809] CONTROL UNIT 4 AD converter system of transfer control unit is mal-
functioning. Refer to
DLN-24
.
[P1810] 4L POSI SW TF Improper signal from neutral-4LO switch is input due
to open or short circuit. Refer to
DLN-28
.
[ P 1 8 11 ] B AT T E R Y V O LTA G E Power supply voltage for transfer control unit is ab-
normally low while driving.
Refer to
DLN-22
.
[P1813] 4WD MODE SW More than two switch inputs are simultaneously de-
tected due to short circuit of 4WD shift switch. Refer to
DLN-31
.
[P1814] 4WD DETECT SWITCH Improper signal from wait detection switch is input
due to open or short circuit. Refer to
DLN-35
.
[P1816] PNP SW/CIRC When transmission range switch signal is malfunc-
tion or communication error between the control
units. Refer to
DLN-38
.
[P1817] SHIFT ACTUATOR  Motor does not operate properly due to open or
short circuit in actuator motor.
 Malfunction is detected in the actuator motor. (When 4WD shift switch is operated and actuator
motor is not operated)
 Malfunction is detected in transfer shift high relay and transfer shift low relay. Refer to
DLN-39
.
[P1818] SHIFT ACT POSI SW  Improper signal from actuator position switch is in-
put due to open or short circuit.
 Malfunction is detected in the actuator position
switch. Refer to
DLN-45
.
[P1819] SHIFT ACT CIR  Transfer control device actuator circuit is shorted
or open. (Malfunctions are detected when transfer
shift relay circuit is open/shorted or relay monitor
circuit is open/shorted.)
 Malfunction occurs in transfer control device drive circuit.
 Malfunction is detected in transfer shut off relay. Refer to
DLN-48
.
[P1820] ENGINE SPEED SIG  Malfunction is detected in engine speed signal
that is output from ECM through CAN communi-
cation.
 Improper signal is input while driving. Refer to
DLN-52
.
[P1822] DUTY SOLENOID Proper voltage is not applied to clutch pressure so-
lenoid valve due to open or short circuit. Refer to
DLN-53
.
[P1823] 2-4WD SOLENOID Proper voltage is not applied to 2-4WD solenoid
valve due to open or short circuit. Refer to
DLN-57
.
[P1824] MOTOR RELAY Motor does not operate properly due to open or
short circuit in transfer motor or transfer motor relay.
Refer to
DLN-61
.
Revision: December 20092009 QX56

TRANSFER CONTROL UNITDLN-99
< ECU DIAGNOSIS > [ATX14B]
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CAUTION:
 If CAN COMM CIRCUIT [U1000] or CONTROL UNIT (CAN) [U1010] is displayed with other DTCs, first perform the trouble
diagnosis for CAN communication line.
 If ABS OP SIG [P1830], VDC OP SIG [P1831] or TCS OP SIG [P1832] is displayed, first perform the trouble diagnosis for ABS system.
 If VHCL SPEED SEN·AT [P1807] is displayed, firs t perform the trouble diagnosis for A/T system.
NOTE:
 If SHIFT ACT POSI SW [P1818] or SHIFT ACT CIR [P1819] is disp layed, first erase self-diagnostic results. (SHIFT ACT POSI SW
[P1818] or SHIFT ACT CIR [P1819] may be displayed after installing transfer control unit or transfer assembly.)
 If CL PRES SW [P1827] or LINE PRES SW [P1828] is displayed only while driving in reverse, check the continuity of R position o n
transmission range switch. When there is no malfunction found in the electrical system, check the hydraulic system.
FLASH CODE CHART
[P1826] OIL TEMP SEN Signal voltage from transfer fluid temperature sen-
sor is abnormally high (Transfer fluid temperature is
abnormally low) while driving. Refer to
DLN-67.
[P1827] CLUTCH PRES SW  Improper signal from clutch pressure switch is in-
put due to open or short circuit.
 Malfunction occurs in clutch pressure switch or
hydraulic circuit. Refer to
DLN-70
.
[P1828] LINE PRES SW  Improper signal from line pressure switch is input
due to open or short circuit.
 Malfunction occurs in line pressure switch or hy-
draulic circuit. Refer to
DLN-73
.
[P1829] THROTTLE POSI SEN  Malfunction is detected in accelerator pedal posi-
tion signal that is output from ECM through CAN
communication.
 Signal voltage from accelerator pedal position sensor is abnormally high or low. Refer to
DLN-76
.
[P1830] ABS OP SIG Malfunction is detected in ABS operation signal that
is output from ABS actuator and electric unit (control
unit) through CAN communication. Refer to
DLN-77
.
[P1831] VDC OP SIG Malfunction is detected in VDC operation signal that
is output from ABS actuator and electric unit (control
unit) through CAN communication.
Refer to
DLN-78
.
[P1832] TCS OP SIG Malfunction is detected in TCS operation signal that
is output from ABS actuator and electric unit (control
unit) through CAN communication. Refer to
DLN-79
.
[U1010] CONTROL UNIT (CAN) Detecting error during the initial diagnosis of CAN
controller of transfer control unit. Refer to
DLN-80
DTC CONSULT-III Diagnostic item is detected when... Reference
Flashing pattern Item Diagnostic item is detected when... Reference
2 Vehicle speed signal
(from A/T)  Malfunction is detected in output shaft revolution signal
that is output from TCM through CAN communication.
 Improper signal is input while driving. Refer to
DLN-26
.
3 Clutch pressure sole-
noid signal Proper voltage is not applied to clutch pressure solenoid
valve due to open or short circuit.
Refer to
DLN-53
.
4 2-4WD solenoid signal Proper voltage is not applied to 2-4WD solenoid valve due
to open or short circuit.
Refer to
DLN-57
.
5 Transfer motor Transfer motor does not operate properly due to open or
short circuit in transfer motor or transfer motor relay. Refer to
DLN-61
.
6 Vehicle speed signal
(from ABS)  Malfunction is detected in vehicle speed signal that is out-
put from ABS actuator and elec tric unit (control unit)
through CAN communication.
 Improper signal is input while driving. Refer to
DLN-27
.
7 CAN communication Malfunction has been detected from CAN communication
line. Refer to
LAN-51
.
Revision: December 20092009 QX56

DLN-100
< ECU DIAGNOSIS >[ATX14B]
TRANSFER CONTROL UNIT
8 AD converterAD converter system of transfer control unit is malfunction-
ing. Refer to
DLN-24.
9 Transfer fluid tempera-
ture Signal voltage from transfer fluid temperature sensor is ab-
normally high (Transfer fluid temperature is abnormally low)
while driving.
Refer to
DLN-67
.
10 Neutral-4LO switch Improper signal from neutral-4LO switch is input due to
open or short circuit. Refer to
DLN-28
.
11 Clutch pressure switch  Improper signal is input due to open or short circuit.
 Malfunction occurs in clutch pressure switch or hydraulic
circuit. Refer to
DLN-70
.
12 Line pressure switch  Improper signal is input due to open or short circuit.
 Malfunction occurs in line pressure switch or hydraulic
circuit. Refer to
DLN-73
.
13 Engine speed signal
(from ECM)  Malfunction is detected in engine speed signal that is out-
put from ECM through CAN communication.
 Improper signal is input while driving. Refer to
DLN-52
.
14 Accelerator pedal posi-
tion sensor (from
ECM)  Malfunction is detected in accelerator pedal position sig-
nal that is output from ECM through CAN communication.
 Signal voltage from accelerator pedal position sensor is abnormally high or low. Refer to
DLN-76
.
15 Power supply Power supply voltage for transfer control unit is abnormally
low while driving.
Refer to
DLN-22
.
16 4WD shift switch More than two switch inputs are simultaneously detected
due to short circuit of 4WD shift switch. Refer to
DLN-31
.
17 ABS operation signal
(from ABS) Malfunction is detected in ABS operation signal that is out-
put from ABS actuator and electric unit (control unit)
through CAN communication.
Refer to
DLN-77
.
18 Wait detection switch Improper signal from wait detection switch is input due to
open or short circuit. Refer to
DLN-35
.
19 Actuator motor  Motor does not operate properly due to open or short cir-
cuit in actuator motor.
 Malfunction is detected in the actuator motor. (When 4WD shift switch is operated and actuator motor is not
operated)
 Malfunction is detected in transfer shift high relay and transfer shift low relay. Refer to
DLN-39
.
20 Actuator position
switch  Improper signal from actuator position switch is input due
to open or short circuit.
 Malfunction is detected in the actuator position switch. Refer to
DLN-45
.
21 Actuator circuit  Transfer control device actuator circuit is shorted or open.
(Malfunctions are detected when motor relay circuit is
open/shorted or relay transfer shift circuit is open/short-
ed.)
 Malfunction occurs in transfer control device drive circuit. Refer to
DLN-48
.
22 VDC operation signal
(from VDC) Malfunction is detected in VDC operation signal that is out-
put from ABS actuator and electric unit (control unit)
through CAN communication.
Refer to
DLN-78
.
23 TCS operation signal
(from TCS) Malfunction is detected in TCS operation signal that is out-
put from ABS actuator and electric unit (control unit)
through CAN communication.
Refer to
DLN-79
.
24 Transmission range
switch signal (from
TCM) When transmission range switch signal is malfunction or
communication error between the control units.
Refer to
DLN-38
.
Repeats flickering
every 2 to 5 sec. — System normal. Refer to
DLN-102
Flashing pattern Item Diagnostic item is detected when... Reference
Revision: December 20092009 QX56

TRANSFER CONTROL UNITDLN-101
< ECU DIAGNOSIS > [ATX14B]
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CAUTION:
 If CAN communication is displayed wi th other DTCs, first perform the trouble diagnosis for CAN communication line.
 If ABS operation signal, VDC operation signal or TCS operation signal is displayed, first perform the trouble diagnosis for ABS system.
 If Output shaft revolution signal is displayed, first perform the trouble diagnosis for A/T system.
NOTE:
 If actuator position switch or actuator circuit is displayed, first erase self-diagnostic results. (Actuator position switch o r actuator circuit
may be displayed after installing transfer control unit or transfer assembly.)
 If clutch pressure switch or line pressure switch is displayed only while driving in reverse, check the continuity of R positi on on trans-
mission range switch. When there is no malfunction found in the electrical system, check the hydraulic system.
Repeats flickering
every 0.25 sec.
Data erase display  Power supply failure of memory back-up.
 Battery performance is poor. Refer to
DLN-22
.
No flickering Transmission range
switch or 4WD shift
switch Transmission range switch or 4WD shift switch circuit is
shorted or open.
Refer to
DLN-38
or
DLN-31
.
Flashing pattern Item Diagnostic item is detected when... Reference
Revision: December 20092009 QX56

DLN-158
< DISASSEMBLY AND ASSEMBLY >[ATX14B]
TRANSFER ASSEMBLY
a. Remove all the bolts except for the two shown.
b. Remove the following from the control valve assembly:
 Clutch pressure solenoid valve
 Clutch pressure switch
 2-4WD shift solenoid valve
 Line pressure switch
 Transfer fluid temperature sensor
c. Remove the O-rings from each solenoid valve, switch and termi- nal body.
d. Place the control valve with the lower body facing up. Remove the two bolts, and then remove the lower body and separator
plate from the upper body.
CAUTION:
Do not drop relief balls. Detach lower body carefully.
e. Make sure the reverse balls, relief balls, relief springs, accumu- lator pistons and valve springs are securely installed as shown,
and remove them.
f. Remove the retainer plates.
WDIA0198E
WDIA0199E
WDIA0200E
SDIA2126E
SDIA2127E
Revision: December 20092009 QX56

TRANSFER ASSEMBLYDLN-165
< DISASSEMBLY AND ASSEMBLY > [ATX14B]
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7. Apply ATF to the new O-ring and install it to the transfer motor. CAUTION:
Do not reuse O-rings.
8. Fit the double-flat end of the transfer motor shaft into the slot of the sub-oil pump assembly. Then tighten to the specified torque.
Refer to DLN-142, "Disassembly and Assembly"
CAUTION:
Be sure to install connector bracket.
9. Apply ATF to the new lip seals, and install them to the center case.
CAUTION:
 Do not reuse lip seals.
 There are 2 kinds of lip seals (lip seal of large inner diam-
eter: 5 pieces, lip seal of small inner diameter: 2 pieces).
Confirm their position for installation.
10. Install the control valve assembly to the center case, and tighten to the specified torque. Refer to DLN-142, "Disassembly and
Assembly".
CAUTION:
 Do not reuse any part that has been dropped or damaged.
 Make sure valve is assembled in the proper direction.
 Do not use a magnet becau se residual magnetism stays
during assembly.
11. Install the connector assembly into the center case, and secure with a snap ring.
12. Apply ATF to the new O-rings, and install them on the oil strainer.
CAUTION:
Do not reuse O-rings.
13. Install the oil strainer to the control valve assembly.
SDIA2787E
SDIA2123E
SDIA2121E
SDIA2122E
SDIA2782E
Revision: December 20092009 QX56

TRANSFER ASSEMBLYDLN-169
< DISASSEMBLY AND ASSEMBLY > [ATX14B]
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29. Install the new snap ring to the main shaft. CAUTION:
Do not reuse snap ring.
30. Install the mainshaft rear bearing to the center case using Tool.
31. Install the mainshaft assembly using a press.  Press the mainshaft into the center case using Tools.
32. Install the C-rings to the mainshaft.
33. Set the washer holder on the mainshaft, and secure it with a new snap ring.
CAUTION:
Do not reuse snap ring.
SDIA2195E
Tool number : ST15310000 (J-25640-B)
SDIA2196E
Tool number A: ST30911000 ( — )
B: ST33052000 ( — )
SDIA2197E
SDIA2201E
SDIA2104E
Revision: December 20092009 QX56

TRANSFER ASSEMBLYDLN-173
< DISASSEMBLY AND ASSEMBLY > [ATX14B]
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5. Install the sun gear assembly to the planetary carrier assembly.
6. Install the new snap ring to the planetary carrier assembly. CAUTION:
Do not reuse snap ring.
7. Set the input bearing into the front case and install using Tool.
8. Install the new snap ring into the front case. CAUTION:
Do not reuse snap ring.
9. Install the internal gear with its groove facing the snap ring into the front case. Then secure it with the new snap ring.
CAUTION:
Do not reuse snap ring.
SDIA2180E
SDIA2794E
Tool number : ST30720000 (J-25405)
SDIA2172E
SDIA2171E
WDIA0100E
Revision: December 20092009 QX56