2008 INFINITI QX56 4WD

DLN-70
< COMPONENT DIAGNOSIS >[ATX14B]
P1827 CLUTCH PRESSURE SWITCH
P1827 CLUTCH PRESSURE SWITCH
DescriptionINFOID:0000000001737159
Improper signal from the clutch pressure switch is i
nput due to open or short circuit. Also, a malfunction may
have occured in clutch pressure switch or hydraulic circuit.
DTC LogicINFOID:0000000001737160
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE
1.DTC CONFIRMATION PROCEDURE
1. Turn ignition switch ON.
2. Perform self-diagnosis.
Is DTC P1827 displayed?
YES >> Perform diagnosis procedure. Refer to DLN-70, "Diagnosis Procedure".
NO >> Inspection End.
Diagnosis ProcedureINFOID:0000000001737161
1.CHECK CLUTCH PRESSURE SWITCH SIGNAL
With CONSULT-III1. Start engine.
2. Select DATA MONITOR mode for ALL MODE AWD/4WD with CONSULT-III.
3. Read out ON/OFF switching action of the CL PRES SW while operating 4WD shift switch.
Without CONSULT-III
1. Start engine.
2. Check voltage between transfer control unit harness connector
terminals and ground.
Are inspection results normal?
DTC CONSULT-III Diagnostic item is detected when... Reference
[P1827] CLUTCH PRES SW • Improper signal from clutch pressure
switch is input due to open or short cir-
cuit.
• Malfunction occurs in clutch pressure switch or hydraulic circuit. Refer to
DLN-70
.
Condition Display value
• Ignition switch: ON
• A/T selector lever D posi- tion 4WD shift switch: AUTO or 4H (Wait
function is not operating.)
ON
Ignition switch: ON 4WD shift switch: 2WD (Wait func-
tion is not operating.) OFF
Connector Terminal ConditionVoltage
(Approx.)
E143 34 -
Ground • Ignition switch: ON
• A/T selector lever D
position 4WD shift switch:
AUTO or 4H (Wait
function is not op-
erating.)
0V
Ignition switch: ON 4WD shift switch:
2WD (Wait function
is not operating.)Battery
voltage
SDIA2746E
Revision: March 2010
2008 QX56

P1828 LINE PRESSURE SWITCHDLN-73
< COMPONENT DIAGNOSIS > [ATX14B]
C
EF
G H
I
J
K L
M A
B
DLN
N
O P
P1828 LINE PRESSURE SWITCH
DescriptionINFOID:0000000001737163
Improper signal from line pressure switch is input due to open or short circuit. Also, a malfunction may have
occured in the line pressure switch or hydraulic circuit.
DTC LogicINFOID:0000000001737164
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE
1.DTC CONFIRMATION PROCEDURE
1. Turn ignition switch ON.
2. Perform self-diagnosis.
Is DTC P1828 displayed?
YES >> Perform diagnosis procedure. Refer to DLN-73, "Diagnosis Procedure".
NO >> Inspection End.
Diagnosis ProcedureINFOID:0000000001737165
1.CHECK LINE PRESSURE SWITCH SIGNAL
With CONSULT-III1. Start engine.
2. Select DATA MONITOR mode for ALL MODE AWD/4WD with CONSULT-III.
3. Read out ON/OFF switching action of LINE PRES SW while operating 4WD shift switch.
Without CONSULT-III
1. Start engine.
2. Check voltage between transfer control unit harness connector
terminals and ground.
DTC CONSULT-III Diagnostic item is detected when... Reference
[P1828] LINE PRES SW • Improper signal from line pressure
switch is input due to open or short cir-
cuit.
• Malfunction occurs in line pressure switch or hydraulic circuit. Refer to DLN-73
.
Condition
Display value
• A/T selector lever D position
• 4WD shift switch: AUTO ON
• Except the above
• The vehicle has been left at room temperature for 5
minutes and more with ig-
nition switch in OFF posi-
tion. • Ignition switch: ON
• A/T selector lever: P or N position
• 4WD shift switch: other than
AUTO OFF
SDIA2751E
Revision: March 2010
2008 QX56

DLN-74
< COMPONENT DIAGNOSIS >[ATX14B]
P1828 LINE PRESSURE SWITCH
Are inspection results normal?
YES >> GO TO 5.
NO >> GO TO 2.
2.CHECK HARNESS BETWEEN TRANSFER CONT
ROL UNIT AND LINE PRESSURE SWITCH
1. Turn ignition switch OFF. (Stay for at least 5 seconds.)
2. Disconnect transfer control unit harness connector and the transfer terminal cord assembly harness con-
nector.
3. Check continuity between transfer control unit harness connec-
tor E143 terminal 35 and transfer terminal cord assembly har-
ness connector F56 terminal 1.
Also check harness for short to ground and short to power.
Are inspection results normal?
YES >> GO TO 3.
NO >> Repair or replace damaged parts.
3.CHECK TRANSFER CONTROL UNIT
Check transfer control unit input/output signal. Refer to DLN-80, "
Reference Value".
Are inspection results normal?
YES >> GO TO 4.
NO >> Check the following. If any items are damaged, repair or replace damaged parts. • Transfer control unit pin terminals for damage or loose connection with harness connector.
• Transfer control unit. Refer to DLN-128, "
Removal and Installation".
4.CHECK LINE PRESSURE SWITCH
1. Turn ignition switch OFF. (Stay for at least 5 seconds.)
2. Remove line pressure switch. Refer to DLN-16, "
Component Parts Location".
3. Push and release line pressure switch and check continuity between terminal 1 and ground.
Are inspection results normal?
YES >> GO TO 5.
NO >> Replace line pressure switch.
5.CHECK DTC
Perform the self-diagnosis, after driving a vehicle for a while.
Connector Terminal ConditionVoltage
(Approx.)
E143 35 -
Ground • A/T selector lever D
position 4WD shift switch:
AUTO
0V
• Except the above
• The vehicle has been left at room
temperature for 5
minutes and more
with ignition switch
in OFF position. • Ignition switch:
ON
• A/T selector le-
ver: P or N posi-
tion
• 4WD shift
switch: other
than AUTO Battery
voltage
Continuity should exist.
SDIA2752E
Terminal
Condition Continuity
1 -
Ground Push line pressure switch
Yes
Release line pressure switch No
WDIA0172E
Revision: March 2010 2008 QX56

DLN-80
< ECU DIAGNOSIS >[ATX14B]
TRANSFER CONTROL UNIT
ECU DIAGNOSIS
TRANSFER CONTROL UNIT
Reference ValueINFOID:0000000001737179
VALUE ON THE DIAGNOSIS TOOL
CONSULT-III data monitor item
Monitored item [Unit]
Content ConditionDisplay value
VHCL/S SEN·FR [km/h]
or [mph] Wheel speed (Front
wheel) Vehicle stopped
0 km/h (0 mph)
Vehicle running
CAUTION:
Check air pressure of tire under standard condition. Approximately
equal to the indica-
tion on speedome-
ter (Inside of
±
10%)
VHCL/S SEN·RR [km/h]
or [mph] Wheel speed (Rear
wheel) Vehicle stopped
0 km/h (0 mph)
Vehicle running
CAUTION:
Check air pressure of tire under standard condition. Approximately
equal to the indica-
tion on speedome-
ter (Inside of
±
10%)
ENGINE SPEED [rpm] Engine speed Engine stopped
(Engine speed: Less than 400 rpm)
0 rpm
Engine running
(Engine speed: 400 rpm or more) Approximately
equal to the indica-
tion on tachometer
THRTL POS SEN [V] Accelerator
pedal posi-
tion (APP) sensor signal
voltage Accelerator pedal: Released
Approx. 0.5V
Accelerator pedal: Fully depressed Approx. 4.0V
FLUID TEMP SE [V] Transfer fluid tempera-
ture signal voltage Transfer fluid temperature approx. 20 - 80
°C (68 - 176 °F) Approx. 1.1 - 0.3V
BATTERY VOLT [V] Power supply voltage for
transfer control unit Ignition switch: ON
Battery voltage
2WD SWITCH [ON/OFF] Input condition from 4WD
shift switch 4WD shift switch: 2WD
ON
4WD shift switch: AUTO, 4H or 4LO OFF
AUTO SWITCH [ON/
OFF] Input condition from 4WD
shift switch 4WD shift switch: AUTO
ON
4WD shift switch: 2WD, 4H or 4LO OFF
LOCK SWITCH [ON/
OFF] Input condition from 4WD
shift switch 4WD shift switch: 4H
ON
4WD shift switch: 2WD, AUTO or 4LO OFF
4L SWITCH [ON/OFF] Input condition from 4WD
shift switch 4WD shift switch: 4LO
ON
4WD shift switch: 2WD, AUTO or 4H OFF
N POSI SW TF [ON/
OFF] Condition of neutral-4LO
switch • Vehicle stopped
• Engine running
• A/T selector lever N posi-
tion
• Brake pedal depressed 4WD shift switch: 2WD,
AUTO or 4H
OFF
4WD shift switch: 4H to
4LO (While actuator mo-
tor is operating.) OFF
→ON
4WD shift switch: 4LO to
4H (While actuator motor
is operating.) ON
→OFF
4WD shift switch: 4LO ON
Revision: March 2010 2008 QX56

TRANSFER CONTROL UNITDLN-81
< ECU DIAGNOSIS > [ATX14B]
C
EF
G H
I
J
K L
M A
B
DLN
N
O P
ATP SWITCH [ON/OFF] Condition of ATP switch • Vehicle stopped
• Engine running
• A/T selector lever N posi-
tion
• Brake pedal depressed 4WD shift switch
: 4H to 4LO or 4LO to 4H
(While actuator motor is
operating.)
ON
Except the above OFF
WAIT DETCT SW [ON/
OFF] Condition of wait detec-
tion switch • Vehicle stopped
• Engine running
• A/T selector lever N posi-
tion
• Brake pedal depressed 4WD shift switch: 2WD,
AUTO or 4H
OFF
4WD shift switch: 4H to
4LO (While actuator mo-
tor is operating.) OFF
→ON
4WD shift switch: 4LO to
4H (While actuator motor
is operating.) ON
→OFF
4WD shift switch: 4LO ON
LINE PRES SW [ON/
OFF] Condition of line pres-
sure switch • A/T selector lever D position
• 4WD shift switch: AUTO
ON
• Except the above
• The vehicle has been left at room temperature for 5
minutes and more with ig-
nition switch in OFF posi-
tion. • Ignition switch: ON
• A/T selector lever: P or
N position
• 4WD shift switch: other than AUTO OFF
CL PRES SW [ON / OFF] Condition of clutch pres-
sure switch • Vehicle stopped
• Engine running
• A/T selector lever D position
• 4WD shift switch: AUTO or 4H (Wait function is not op-
erating.) ON
• Vehicle stopped
• Engine running
• 4WD shift switch: 2WD (Wait function is not operating.) OFF
N POSI SW AT [ON/
OFF] Input condition from A/T
transmission range
switch • Vehicle stopped
• Engine running
• Brake pedal depressed A/T selector lever posi-
tion: N
ON
Except the above OFF
R POSI SW AT [ON/
OFF] Input condition from A/T
transmission range
switch • Vehicle stopped
• Engine running
• Brake pedal depressed A/T selector lever posi-
tion: R
ON
Except the above OFF
P POSI SW AT [ON/OFF] Input condition from A/T
transmission range
switch • Vehicle stopped
• Engine running
• Brake pedal depressed A/T selector lever posi-
tion: P
ON
Except the above OFF
ABS OPER SW [ON/
OFF] Condition of ABS operat-
ing ABS is operating.
ON
ABS is not operating. OFF
VDC OPE R
SW [O

N/
OFF] Condition of VDC operat-
ing VDC is operating.
ON
VDC is not operating. OFF
TCS OPER SW [ON/
OFF] Condition of TCS operat-
ing TCS is operating.
ON
TCS is not operating. OFF
THROTTLE POSI [0.0/8] Condition of throttle
opening When depressing accelerator pedal
(Value rises gradually in response to throttle position.)
0.0/8 - 8.0/8
4WD MODE [AUTO/
LOCK/2WD/4L] Control status of 4WD
(Output condition of 4WD
shift indicator lamp and
4LO indicator lamp) • Vehicle stopped
• Engine running
• A/T selector lever N posi-
tion
• Brake pedal depressed 4WD shift switch: 2WD
2WD
4WD shift switch: AUTO AUTO
4WD shift switch: 4H LOCK
4WD shift switch: 4LO 4L
Monitored item [Unit]
Content ConditionDisplay value
Revision: March 2010 2008 QX56

DLN-82
< ECU DIAGNOSIS >[ATX14B]
TRANSFER CONTROL UNIT
VHCL/S COMP [km/h] or
[mph]Vehicle speed Vehicle stopped
0 km/h (0 mph)
Vehicle running
CAUTION:
Check air pressure of tire under standard condition. Approximately
equal to the indica-
tion on speedome-
ter (Inside of
±
10%)
COMP CL TORQ [kgm] Condition of control
torque • Vehicle stopped
• Engine running
• A/T selector lever N posi-
tion
• Brake pedal depressed 4WD shift switch: 2WD 0 kg-m
4WD shift switch: AUTO
39 - 1,353 N·m
(4 - 138 kg-m, 29 - 998 ft-lb)
4WD shift switch: 4H or
4LO 1,353 N·m
(138 kg-m, 998 ft-
lb)
DUTY SOLENOID [%] Condition of clutch pres-
sure solenoid • Vehicle stopped
• Engine running
• A/T selector lever N posi-
tion
• Brake pedal depressed 4WD shift switch: 2WD
4%
4WD shift switch: AUTO 96 - 4%
4WD shift switch: 4H or
4LO 4%
2-4WD SOL [ON/OFF] Condition of 2-4WD shift
solenoid valve • Vehicle stopped
• Engine running
• A/T selector lever N posi-
tion
• Brake pedal depressed 4WD shift switch: 2WD
OFF
4WD shift switch: AUTO ON
4WD shift switch: 4H
4WD shift switch: 4LO
4WD shift switch: AUTO
(Wait function is operat-
ing.) OFF
4WD shift switch: 4H
(Wait function is operat-
ing.) OFF
2-4WD SOL MON [ON/
OFF] Check signal for transfer
control unit signal output • Vehicle stopped
• Engine running
• A/T selector lever N posi-
tion
• Brake pedal depressed 4WD shift switch: 2WD
OFF
4WD shift switch: AUTO ON
4WD shift switch: 4H
4WD shift switch: 4LO
4WD shift switch: AUTO
(Wait function is operat-
ing.) OFF
4WD shift switch: 4H
(Wait function is operat-
ing.) OFF
MOTOR RELAY [ON/
OFF] Condition of transfer mo-
tor relay • Accelerator pedal de-
pressed
• Vehicle stopped
• Engine running
• Brake pedal depressed 4WD shift switch: 2WD
OFF
4WD shift switch: AUTO
or 4LO (A/T selector lever
P or N position) OFF
(ON for approx. 2 sec. after shifting to P and N.)
4WD shift switch: AUTO
or 4LO (Except for A/T se-
lector lever P or N posi-
tion) ON
4WD shift switch: 4H (A/T
selector lever P position) OFF
(ON fo r appro
x
. 2
sec. after shifting to P.)
4WD shift switch: 4H (Ex-
cept for A/T selector lever
P position) ON
Monitored item [Unit]
Content ConditionDisplay value
Revision: March 2010 2008 QX56

TRANSFER CONTROL UNITDLN-83
< ECU DIAGNOSIS > [ATX14B]
C
EF
G H
I
J
K L
M A
B
DLN
N
O P
MOTOR RELAY MON
[ON/OFF] Check signal for transfer
control unit signal output • Accelerator pedal de-
pressed
• Vehicle stopped
• Engine running
• Brake pedal depressed 4WD shift switch: 2WD
OFF
4WD shift switch: AUTO
or 4LO (A/T selector lever
P or N position) OFF
(ON for approx. 2
sec. after shifting to P and N.)
4WD shift switch: AUTO
or 4LO (Except for A/T se-
lector lever P or N posi-
tion) ON
4WD shift switch: 4H (A/T
selector lever P position) OFF
(ON for approx. 2
sec. after shifting to P.)
4WD shift switch: 4H (Ex-
cept for A/T selector lever
P position) ON
4WD FAIL LAMP [ON/
OFF] Condition of 4WD warn-
ing lamp 4WD warning lamp: ON
ON
4WD warning lamp: OFF OFF
2WD IND [ON/OFF] Condition of 4WD shift in-
dicator lamp (2WD indi-
cator lamp) 2WD indicator lamp of 4WD shift indicator lamp: OFF
OFF
2WD indicator lamp of 4WD shift indicator lamp: ON ON
AUTO IND [ON/OFF] Condition of 4WD shift in-
dicator lamp (AUTO indi-
cator lamp) AUTO indicator lamp of 4WD shift indicator lamp: OFF
OFF
AUTO indicator lamp of 4WD shift indicator lamp: ON ON
LOCK IND [ON/OFF] Condition of 4WD shift in-
dicator lamp
(Lock indi-
cator lamp) Lock indicator lamp of 4WD shift indicator lamp: OFF
OFF
Lock indicator lamp of 4WD shift indicator lamp: ON ON
4L IND [ON/OFF] Condition of 4LO indica-
tor lamp condition 4LO indicator lamp: OFF
OFF
4LO indicator lamp: ON ON
ATP IND [ON/OFF] Condition of ATP indica-
tor lamp ATP indicator lamp: ON
ON
ATP indicator lamp: OFF OFF
SHIFT POS SW1 [ON/
OFF] Condition of actuator po-
sition switch 1
(Low) • Vehicle stopped
• Engine running
• A/T selector lever N posi-
tion
• Brake pedal depressed 4WD shift switch: 4LO
ON
4WD shift switch: 2WD,
AUTO or 4H OFF
SHIFT POS SW2 [ON/
OFF] Condition of actuator po-
sition switch 2
(High) • Vehicle stopped
• Engine running
• A/T selector lever N posi-
tion
• Brake pedal depressed 4WD shift switch: 4H,
AUTO or 2WD
ON
4WD shift switch: 4LO OFF
SHIFT ACT1 [ON/OFF] Output condition to actu-
ator motor (High) • Vehicle stopped
• Engine running
• A/T selector lever N posi-
tion
• Brake pedal depressed 4WD shift switch: 4H to
4LO (Wait function is op-
era
ti
ng.

) ON
Except the above OFF
SHIFT AC MON1 [ON/
OFF] Check signal for transfer
control unit signal output • Vehicle stopped
• Engine running
• A/T selector lever N posi-
tion
• Brake pedal depressed 4WD shift switch: 4H to
4LO (Wait function is op-
erating.)
ON
Except the above OFF
SHIFT ACT2 [ON/OFF] Output condition to actu-
ator motor (Low) • Vehicle stopped
• Engine running
• A/T selector lever N posi-
tion
• Brake pedal depressed 4WD shift switch: 4LO to
4H (Wait function is oper-
ating.)
ON
Except the above OFF
Monitored item [Unit]
Content ConditionDisplay value
Revision: March 2010 2008 QX56

DLN-84
< ECU DIAGNOSIS >[ATX14B]
TRANSFER CONTROL UNIT
PHYSICAL VALUES
Terminal Layout
SHIFT AC MON2 [ON/
OFF]Check signal for transfer
control unit signal output • Vehicle stopped
• Engine running
• A/T selector lever N posi-
tion
• Brake pedal depressed 4WD shift switch: 4LO to
4H (Wait function is oper-
ating.)
ON
Except the above OFF
T/F F SPEED [km/h] or
[mph] Displayed, but do not use.
A/T R SPEED [km/h] or
[mph] Condition of vehicle
speed sensor A/T (Out-
put speed sensor)
During driving Approximately
matches the out-
put shaft speed.
AT GEAR POSI [1/2/3/4/
5] Condition of A/T selector
lever position
Displays actual A/T gear position. 1
2
3
4
5
Monitored item [Unit]
Content ConditionDisplay value
WDIA0378E
Te r m i n a lWire
color Item
ConditionData (Approx.)
1 GR 2-4WD shift solenoid valve • Vehicle stopped
• Engine running
• A/T selector lever
“N” position
• Brake pedal de- pressed 4WD shift switch: 2WD
0V
4WD shift switch: AUTO, 4H or 4LO Battery voltage
2 B/W 4WD shift indicator lamp
(2WD indica
tor lamp) 2WD indicator lamp: OFF
Battery voltage
2WD indicator lamp: ON 0V
3 B Ground Always0V
4 Y/L Transfer shift high relay • 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
5 W/B 4WD warning lamp 4WD warning lamp: ON
0V
4WD warning lamp: OFF Battery voltage
6 B Ground Always0V
7 L CAN-H ——
8 P CAN-L ——
9G/W 4WD shift switch
(2WD) Ignition switch: ON4WD shift switch: 2WD
Battery voltage
4WD shift switch: AUTO, 4H or 4LO 0V
Revision: March 2010 2008 QX56