2008 INFINITI QX56 engine

P1824 TRANSFER MOTORDLN-63
< COMPONENT DIAGNOSIS > [ATX14B]
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Are the inspection results normal?
YES >> GO TO 7.
NO >> GO TO 2.
2.CHECK TRANSFER MOTOR RELAY POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF. (Stay for at least 5 seconds.)
2. Connect transfer control unit harness connector.
3. Disconnect transfer motor relay.
4. Check voltage between transfer motor relay harness connector terminals and ground.
5. Turn ignition switch ON. (Do not start engine.)
6. Check voltage between transfer motor relay harness connector terminals and ground.
Are the inspection results normal?
YES >> GO TO 3.
NO >> Check the following. If any items are damaged, repair or replace damaged parts.
• 20A fuse (No. 58 located in the fuse and relay box).
• 10A fuse (No. 26 located in the fuse and fusible link box).
• Harness for short or open between battery and transfer motor relay harness connector E154 ter- minal 5.
• Harness for short or open between transfer shut off relay harness connector E69 terminal 5 and transfer motor relay harness connector E153 terminal 2.
E143 41 -
Ground • Accelera-
tor pedal
depressed
• Vehicle
stopped
•Engine running
•Brake pedal de-
pressed 4WD shift switch:
2WD
0V
4WD shift switch:
AUTO or 4LO (A/T
selector lever P or N
position) 0V
(Battery voltage
for approx. 2 sec.
after shifting to P
and N.)
4WD shift switch:
AUTO or 4LO (Ex-
cept for A/T selector
lever P or N position) Battery voltage
4WD shift switch: 4H
(A/T selector lever P
position) 0V
(Battery voltage
for approx. 2 sec.
after shifting to P.)
4WD shift switch: 4H
(Except for A/T se-
lector lever P posi-
tion) Battery voltage
Connector Terminal
ConditionVoltage (Approx.)
Connector Terminal Voltage (Approx.)
E153 2 - Ground 0V
E154 5 - Ground Battery voltage
WDIA0169E
ConnectorTerminal Voltage (Approx.)
E153 2 - Ground
Battery voltage
E154 5 - Ground
WDIA0170E
Revision: March 2010 2008 QX56

P1826 TRANSFER FLUID TEMPERATUREDLN-67
< COMPONENT DIAGNOSIS > [ATX14B]
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P1826 TRANSFER FLUID TEMPERATURE
DescriptionINFOID:0000000001737155
Signal voltage from the transfer fluid temperature sens or is abnormally high (Transfer fluid temperature is
abnormally low) while driving.
DTC LogicINFOID:0000000001737156
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE
1.DTC CONFIRMATION PROCEDURE
1. Turn ignition switch ON.
2. Perform self-diagnosis.
Is DTC P1826 displayed?
YES >> Perform diagnosis procedure. Refer to DLN-67, "Diagnosis Procedure".
NO >> Inspection End.
Diagnosis ProcedureINFOID:0000000001737157
1.CHECK TRANSFER FLUID TE MPERATURE SENSOR SIGNAL
With CONSULT-III
1. Start engine.
2. Select DATA MONITOR mode for ALL MODE AWD/4WD with CONSULT-III.
3. Read out the value of FLUID TEMP SE.
Without CONSULT-III
1. Start engine.
2. Check voltage between transfer control unit harness connector
terminals and ground.
Are inspection results normal?
YES >> GO TO 4.
NO >> GO TO 2.
2.CHECK HARNESS BETWEEN TRANSF ER CONTROL UNIT AND TRANSFER TERMINAL CORD AS-
DTCCONSULT-III Diagnostic item is detected when... Reference
[P1826] OIL TEMP SEN Signal voltage from transfer fluid temper-
ature sensor is abnormally high (Trans-
fer fluid temperature is abnormally low)
while driving.Refer to DLN-67
.
Condition
Display value
(Approx.)
Transfer fluid temperature approx. 20 - 80 °C (68 - 176° F) 1.1 - 0.3V
Connector Terminal ConditionData
(Approx.)
E143 28 -
Ground Always
0V
31 -
Ground Ignition switch:
ON Transfer fluid temperature
approx. 20
°C (68 °F) 1.1V
Transfer fluid temperature
approx. 80 °C (176 °F) 0.3V
SDIA2742E
Revision: March 2010
2008 QX56

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]
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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-76
< COMPONENT DIAGNOSIS >[ATX14B]
P1829 THROTTLE POSITION SIGNAL (ECM)
P1829 THROTTLE POSITION SIGNAL (ECM)
DescriptionINFOID:0000000001737167
Malfunction is detected in accelerator pedal position si
gnal that is output from ECM through CAN communica-
tion. Also, the signal voltage from accelerator pedal position sensor may be abnormally high or low.
DTC LogicINFOID:0000000001737168
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE
1.DTC CONFIRMATION PROCEDURE
1. Turn ignition switch ON.
2. Perform self-diagnosis.
Is DTC P1829 displayed?
YES >> Perform diagnosis procedure. Refer to DLN-76, "Diagnosis Procedure".
NO >> Inspection End.
Diagnosis ProcedureINFOID:0000000001737169
1.CHECK DTC WITH ECM
Perform self-diagnosis with ECM. Refer to EC-63, "
CONSULT-III Function (ENGINE)".
Is any malfunction detec ted by self-diagnosis?
YES >> Check the malfunctioning system.
NO >> GO TO 2.
2.CHECK TRANSFER CONTROL UNIT
Check transfer control unit input/output signal. Refer to DLN-80, "
Reference Value".
Are inspection results normal?
YES >> GO TO 3.
NO >> Check transfer control unit pin terminals fo r damage or loose connection with harness connector.
If any items are damaged, repair or replace damaged parts.
3.CHECK DTC
Perform the self-diagnosis, after driving a vehicle for a while.
Are inspection results normal?
YES >> Inspection End.
NO >> Perform self-diagnosis with ECM again.
DTC CONSULT-III Diagnostic item is detected when... Reference
[P1829] THROTTLE POSI SEN • Malfunction is detected in accelerator
pedal position signal that is output
from ECM through CAN communica-
tion.
• Signal voltage from accelerator pedal position sensor is abnormally high or
low. Refer to
DLN-76
.
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]
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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