2008 INFINITI QX56 4WD

TRANSFER CONTROL UNITDLN-85
< ECU DIAGNOSIS > [ATX14B]
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10 L/W Transfer dropping resistor • Vehicle stopped
• Engine running
• A/T selector lever
“N” position
• Brake pedal de- pressed 4WD shift switch: AUTO
4 - 14V
4WD shift switch: 2WD, 4H or 4LO Less than 1V
11 L 4WD shift indicator lamp
(Lock indicator lamp) Lock indicator lamp of 4WD shift indicator lamp: OFF
Battery voltage
Lock indicator lamp of 4WD shift indicator lamp: ON 0V
12 W/G 4LO indicator lamp 4LO indicator lamp: OFF
Battery voltage
4LO indicator lamp: ON 0V
13 G/B Transfer shift low relay • Vehicle stopped
• Engine running
• A/T selector lever
“N” position
• Brake pedal de-
pressed 4WD shift switch: 4LO to 4H (“Wait” func-
tion is operating.)
Battery voltage
Except the above 0V
14 LG Transfer motor relay • Accelerator pedal
depressed
• Vehicle stopped
• Engine running
• Brake pedal de- pressed 4WD shift switch: 2WD
Battery voltage
4WD shift switch: AUTO or 4LO (A/T selec-
tor lever “P” or “N” position) Battery voltage
(0V for approx.
2 sec. after
shifting to “P”
and “N”.)
4WD shift switch: AUTO or 4LO (Except for
A/T selector lever “P” or “N” position) 0V
4WD shift switch: 4H (A/T selector lever
“P” position) Battery voltage
(0V for approx.
2 sec. after
shifting to “P”.)
4WD shift switch: 4H (Except for A/T selec-
tor lever “P” position) 0V
15 L/B ATP warning lamp ATP indicator lamp: ON
0V
ATP indicator lamp: OFF Battery voltage
16 Y/R Power supply Ignition switch: ON
Battery voltage
Ignition switch: OFF 0V
18 O 4WD shift switch
(4H) Ignition switch: ON4WD shift switch: 4H
Battery voltage
4WD shift switch: 2WD, AUTO or 4LO 0V
19 L Clutch pressure solenoid
valve • Vehicle stopped
• Engine running
• A/T selector lever
“N” position
• Brake pedal de- pressed 4WD shift switch: AUTO
1.5 - 3V
4WD shift switch: 2WD, 4H or 4LO Less than 1V
21 BR 4WD shift indicator lamp
(AUTO indicator lamp) • AUTO indicator lamp of 4WD shift indicator lamp: OFF
Battery voltage
AUTO indicator lamp of 4WD shift indicator lamp: ON 0V
22 Y/R Power supply Ignition switch: ON
Battery voltage
Ignition switch: OFF 0V
23 R 4WD shift switch
(4LO)
Ignition switch: ON4WD shift switch: 4LO
Battery voltage
4WD shift switch: 2WD, AUTO or 4H 0V
24 LG/R 4WD shift switch
(AUTO)
Ignition switch: ON4WD shift switch: AUTO
Battery voltage
4WD shift switch: 2WD, 4H or 4LO 0V
Te r m i n a l
Wire
color Item
ConditionData (Approx.)
Revision: March 2010 2008 QX56

DLN-86
< ECU DIAGNOSIS >[ATX14B]
TRANSFER CONTROL UNIT
25 V Neutral-4LO switch• Vehicle stopped
• Engine running
• A/T selector lever
“N” position
• Brake pedal de- pressed 4WD shift switch: 2WD, AUTO or 4H Battery voltage
4WD shift switch: 4H to 4LO (While actua-
tor motor is operating.)
Battery voltage
→
0V
4WD shift switch: 4LO to 4H (While actua-
tor motor is operating.) 0V
→ Battery
voltage
4WD shift switch: 4LO 0V
27 W/L Actuator position switch 2
(High) • Vehicle stopped
• Engine running
• A/T selector lever
“N” position
• Brake pedal de-
pressed 4WD shift switch: 4H, AUTO or 2WD 0V
4WD shift switch: 4LO
Battery voltage
28 B/G Sensor ground Always0V
29 L/W Ignition switch monitor Ignition switch: ON
Battery voltage
Ignition switch: OFF 0V
30 SB Shut off relay Ignition switch: ON
0V
Ignition switch: OFF Battery voltage
31 G Transfer fluid temperature
sensor
Ignition switch: ONTransfer fluid temperature approx. 20
°C
(68 °F) 1.1V
Transfer fluid temperature approx. 80 °C
(176 °F) 0.3V
33 R/L Transfer shift high relay
monitor • Vehicle stopped
• Engine running
• A/T selector lever
“N” position
• Brake pedal de- pressed 4WD shift switch: 4H to 4LO (“Wait” func-
tion is operating.)
Battery voltage
Except the above 0V
34 BR Clutch pressure switch • Vehicle stopped
• Engine running
• A/T selector lever
“D” position 4WD shift switch: AUTO or 4H (“Wait” func-
tion is not operating.)
0V
• Vehicle stopped
• Engine running 4WD shift switch: 2WD (“Wait” function is
not operating.)
Battery voltage
35 BR/
W Line pressure switch • Ignition switch: ON
• A/T selector lever “D” position
• 4WD shift switch: AUTO
0V
• After the vehicle has been left at
room temperature
for 5 minutes and
more with ignition
switch in “OFF” po-
sition. • Ignition switch: ON
• A/T selector lever: “P” or "N" position
• 4WD shift switch: other than AUTO
Battery voltage
40 L ATP switch • Vehicle stopped
• Engine running
• A/T selector lever
“N”
• Brak e

pedal de-
pressed 4WD shift switch: 4H to 4LO or 4LO to 4H
(While actuator motor is operating.)
0V
Except the above Battery voltage
Te r m i n a l
Wire
color Item
ConditionData (Approx.)
Revision: March 2010 2008 QX56

TRANSFER CONTROL UNITDLN-87
< ECU DIAGNOSIS > [ATX14B]
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CAUTION:
When using a circuit tester to measure voltage for inspection , be sure not to extend forcibly any connector terminals.
NOTE:
Data are reference value and are measured between each terminal and ground.
41 RTransfer motor relay moni-
tor • Accelerator pedal
depressed
• Vehicle stopped
• Engine running
• Brake pedal de- pressed 4WD shift switch: 2WD
0V
4WD shift switch: AUTO or 4LO (A/T selec-
tor lever “P” or “N” position) 0V
(Battery volt-
age for approx.
2 sec. after
shifting to “P”
and “N”.)
4WD shift switch: AUTO or 4LO (Except for
A/T selector lever “P” or “N” position) Battery voltage
4WD shift switch: 4H (A/T selector lever
“P” position) 0V
(Battery volt-
age for approx.
2 sec. after
shifting to “P”.)
4WD shift switch: 4H (Except for A/T selec-
tor lever “P” position) Battery voltage
42 P/G Transfer shift low relay
monitor • Vehicle stopped
• Engine running
• A/T selector lever
“N” position
• Brake pedal de-
pressed 4WD shift switch: 4LO to 4H (“Wait” func-
tion is operating.)
Battery voltage
Except the above 0V
43 G/Y Wait detection switch • Vehicle stopped
• Engine running
• A/T selector lever
“N” position
• Brake pedal de- pressed 4WD shift switch: 2WD, AUTO or 4H Battery voltage
4WD shift switch: 4H to 4LO (While actua-
tor motor is operating.)
Battery voltage
→ 0V
4WD shift switch: 4LO to 4H (While actua-
tor motor is operating.) 0V
→ Battery
voltage
4WD shift switch: 4LO 0V
44 LG/B Actuator position switch 1
(Low) • Vehicle stopped
• Engine running
• A/T selector lever
“N” position
• Brake pedal de- pressed 4WD shift switch: 4LO
0V
4WD shift switch: 2WD, AUTO or 4H Battery voltage
45 B Ground Always0V
47 W Power supply
(Memory back-up) Ignition switch: ON
Battery voltage
Ignition switch: OFF Battery voltage
Te r m i n a l
Wire
color Item
ConditionData (Approx.)
Revision: March 2010 2008 QX56

DLN-96
< 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 speed sensor
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: March 2010
2008 QX56

TRANSFER CONTROL UNITDLN-97
< 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 [P 1832] 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
.
DTC CONSULT-III Diagnostic item is detected when... Reference
Flashing pattern
ItemDiagnostic item is detected when... Reference
2 Vehicle speed signal
(from A/T) • Malfunction is detected in output speed sensor 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 electric 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
.
8 AD converter AD converter system of transfer control unit is malfunction-
ing. Refer to DLN-24
.
Revision: March 2010
2008 QX56

DLN-98
< ECU DIAGNOSIS >[ATX14B]
TRANSFER CONTROL UNIT
9Transfer 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-100
Flashing pattern
ItemDiagnostic item is detected when... Reference
Revision: March 2010 2008 QX56

TRANSFER CONTROL UNITDLN-99
< ECU DIAGNOSIS > [ATX14B]
C
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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 si gnal is displayed, first perform the trouble diagnosis for
ABS system.
• If Output speed sensor 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
ItemDiagnostic item is detected when... Reference
Revision: March 2010 2008 QX56

DLN-100
< SYMPTOM DIAGNOSIS >[ATX14B]
4WD SYSTEM SYMPTOMS
SYMPTOM DIAGNOSIS
4WD SYSTEM SYMPTOMS
Symptom TableINFOID:0000000001737182
If 4WD warning lamp turns ON, perform self-diagnosis. Refer to DLN-18, "CONSULT-III Function (ALL MODE AWD/4WD)".
NOTE:
• Light tight-corner braking symptom may occur depending on driving conditions in AUTO mode. This is not a
malfunction.
• Heavy tight-corner braking symptom occurs when vehicle is driven in the following conditions: 4WD shift
switch is 4H or 4LO, steering wheel is turned fully to either side.
Symptom ConditionReference page
4WD shift indicator lamp and 4LO indicator lamp do not turn ON
(4WD shift indicator lamp and 4LO indicator lamp check) Ignition switch: ON
DLN-101
4WD warning lamp does not turn ON
(4WD warning lamp check) Ignition switch: ON
DLN-103
4WD shift indicator lamp or 4LO indicator lamp does not change Engine runningDLN-105
ATP warning lamp does not turn ON Engine runningDLN-107
4WD shift indicator lamp keeps flashing Engine runningDLN-109
4WD warning lamp flashes rapidly (2 times/second) While drivingDLN-110
4WD warning lamp flashes slowly
(1 time/2 seconds) While driving
DLN-111
Heavy tight-corner braking symptom occurs
(See NOTE.) • While driving
•AUTO mode
• Steering wheel is turned fully
to either side DLN-112
ATP switch does not operate
Engine runningDLN-114
4WD system does not operate While drivingDLN-116
Revision: March 2010 2008 QX56