2010 INFINITI QX56 4WD

DLN-22
< COMPONENT DIAGNOSIS >[ATX14B]
P1811 POWER SUPPLY CIRCUIT
FOR TRANSFER CONTROL UNIT
COMPONENT DIAGNOSIS
P1811 POWER SUPPLY CIRCUIT FOR TRANSFER CONTROL UNIT
DescriptionINFOID:0000000005148775
Power supply to transfer control unit is abnormally low while driving.
DTC LogicINFOID:0000000005148776
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE
1.DTC CONFIRMATION PROCEDURE
1. Turn ignition switch ON.
2. Perform self-diagnosis.
Is DTC P1811 detected?
YES >> Perform diagnosis procedure. Refer to DLN-22, "Diagnosis Procedure".
NO >> Inspection End.
Diagnosis ProcedureINFOID:0000000005148777
Regarding Wiring Diagram information, refer to DLN-89, "Wiring Diagram - ALL-MODE 4WD SYSTEM -".
1.CHECK POWER SUPPLY
1. Turn ignition switch OFF. (Stay for at least 5 seconds.)
2. Connect transfer control unit harness connector.
3. Check voltage between transfer control unit harness connector terminals and ground.
4. Turn ignition switch ON. (Do not start engine.)
5. Check voltage between transfer control unit harness connector terminals and ground.
DTC CONSULT-III Diagnostic item is detected when... Reference
[ P 1 8 11 ] B AT T E R Y V O LTA G E Power supply voltage for transfer control
unit is abnormally low while driving.Refer to
DLN-22
.
Connector Terminal Voltage (Approx.)
E142 16 - Ground
0V
22 - Ground
E143 29 - Ground
30 - Ground
Battery voltage
47 - Ground
WDIA0165E
Connector Terminal Voltage (Approx.)
E142 16 - Ground
Battery voltage
22 - Ground
E143 29 - Ground
30 - Ground
0V
47 - Ground Battery voltage
WDIA0166E
Revision: April 20092010 QX56

P1802 – P1804, P1809 TRANSFER CONTROL UNIT
DLN-25
< COMPONENT DIAGNOSIS > [ATX14B]
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DLN
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P1802 – P1804, P1809 TRANSFER CONTROL UNIT
DescriptionINFOID:0000000005148779
The transfer control unit controls the transfer control device which controls shifts between AUTO, 4H and 4LO
and between 2WD and 4WD. A DTC may se t when any of the following occur:
• Malfunction is detected in the memory (RAM) system of transfer control unit.
• Malfunction is detected in the memory (ROM) system of transfer control unit.
• Malfunction is detected in the memory (EEPROM) system of transfer control unit.
• AD converter system of transfer control unit is malfunctioning.
DTC LogicINFOID:0000000005148780
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE
1.DTC CONFIRMATION PROCEDURE
1. Turn ignition switch ON.
2. Perform self-diagnosis.
Are DTC's P1802 - P1804 or P1809 detected?
YES >> Perform diagnosis procedure. Refer to DLN-25, "Diagnosis Procedure".
NO >> Inspection End.
Diagnosis ProcedureINFOID:0000000005148781
1.INSPECTION START
Do you have CONSULT-III?
YES or NO
YES >> GO TO 2.
NO >> GO TO 3.
2.PERFORM SELF-DIAGNOSIS (WITH CONSULT-III)
With CONSULT-III
1. Turn ignition switch ON. (Do not start engine.)
2. Select SELF-DIAG RESULTS mode for ALL MODE AWD/4WD with CONSULT-III.
3. Touch ERASE.
4. Turn ignition switch OFF and wait at least 10 seconds.
5. Perform the self-diagnosis again.
Is the CONTROL UNIT 1 [P1802], CONTROL UNIT 2 [P1803], CONTROL UNIT 3 [P1804] or CONTROL
UNIT 4 [P1809] displayed?
YES >> Replace transfer control unit. Refer to DLN-130, "Removal and Installation".
NO >> Inspection End.
3.PERFORM SELF-DIAGNOSIS (WITHOUT CONSULT-III)
DTCCONSULT-III Diagnostic item is detected when... Reference
[P1802] CONTROL UNIT 1 Malfunction is detected in the memory
(RAM) system of transfer control unit.
Refer to DLN-25
.
[P1803] CONTROL UNIT 2
Malfunction is detected in the memory
(ROM) system of transfer control unit.
[P1804] CONTROL UNIT 3 Malfunction is detected in the memory
(EEPROM) system of transfer control
unit.
[P1809] CONTROL UNIT 4 AD converter system of transfer control
unit is malfunctioning.
Revision: April 20092010 QX56

DLN-26
< COMPONENT DIAGNOSIS >[ATX14B]
P1802 – P1804, P1809 TRANSFER CONTROL UNIT

Without CONSULT-III
1. Perform the self-diagnosis and then erase self-diagnostic results. Refer to DLN-18, "CONSULT-III Func-
tion (ALL MODE AWD/4WD)".
2. Perform the self-diagnosis again.
Do the self-diagnostic results indicate AD converter?
YES >> Replace transfer control unit. Refer to DLN-130, "Removal and Installation".
NO >> Inspection End.
Revision: April 20092010 QX56

P1810 NEUTRAL-4LO SWITCHDLN-29
< COMPONENT DIAGNOSIS > [ATX14B]
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P1810 NEUTRAL-4LO SWITCH
DescriptionINFOID:0000000005148788
The neutral-4LO switch detects that the transfer case is in neutral or 4LO range. DTC P1810 will set when an
improper signal from the neutral-4LO switch is input due to an open or short circuit.
DTC LogicINFOID:0000000005148789
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE
1.DTC CONFIRMATION PROCEDURE
1. Turn ignition switch ON.
2. Perform self-diagnosis.
Is DTC P1810 displayed?
YES >> Perform diagnosis procedure. Refer to DLN-29, "Diagnosis Procedure".
NO >> Inspection End.
Diagnosis ProcedureINFOID:0000000005148790
Regarding Wiring Diagram information, refer to DLN-89, "Wiring Diagram - ALL-MODE 4WD SYSTEM -".
1.CHECK 4LO POSITION SWITCH SIGNAL
With CONSULT-III1. Start engine.
2. Select DATA MONITOR mode for ALL MODE AWD/4WD with CONSULT-III.
3. Read out the value of N POSI SW TF.
Without CONSULT-III
1. Start engine.
DTCCONSULT-III Diagnostic item is detected when... Reference
[P1810] 4L POSI SW TF Improper signal from neutral-4LO switch
is input due to open or short circuit.Refer to DLN-29
.
Condition
Display value
• Vehicle stopped
• Engine running
• A/T selector lever N position
• 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: April 20092010 QX56

DLN-30
< COMPONENT DIAGNOSIS >[ATX14B]
P1810 NEUTRAL-4LO SWITCH
2. Check voltage between transfer control unit harness connector
terminal and ground.
Are inspection results normal?
YES >> GO TO 5.
NO >> GO TO 2.
2.CHECK HARNESS BETWEEN TRANSFER CO NTROL UNIT AND NEUTRAL-4LO SWITCH
1. Turn ignition switch OFF. (Stay for at least 5 seconds.)
2. Disconnect transfer control unit harness connecto r and the neutral-4LO switch harness connector.
3. Check continuity between transfer control unit harness connec-
tor E143 terminal 25 and neutral-4LO switch harness connector
F60 terminal 13.
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 GROUND CIRCUIT
1. Turn ignition switch OFF. (Stay for at least 5 seconds.)
2. Disconnect neutral-4LO switch harness connector.
3. Check continuity between neutral-4LO switch harness connec- tor F60 terminal 12 and ground.
Also check harness for short to ground and short to power.
Are inspection results normal?
YES >> GO TO 4.
NO >> Repair open circuit or short to ground or short to power in harness or connectors.
4.CHECK 4LO SWITCH
1. Turn ignition switch OFF.
2. Disconnect neutral-4LO switch harness connector.
3. Remove neutral-4LO switch.
Connector Te r m i n a l
(Wire col- or) Condition
Voltage
(Approx.)
E143 25 -
Ground • 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 actuator
motor is operating.) Battery
voltage
→ 0V
4WD shift switch: 4LO
to 4H (While actuator
motor is operating.) 0V
→
Battery
voltage
4WD shift switch: 4LO 0V
SDIA2693E
Continuity should exist.
SDIA2694E
Continuity should exist.
SDIA2695E
Revision: April 20092010 QX56

DLN-32
< COMPONENT DIAGNOSIS >[ATX14B]
P1813 4WD SHIFT SWITCH
P1813 4WD SHIFT SWITCH
DescriptionINFOID:0000000005148792
The 4WD shift switch allows the driver to select
AUTO, 2WD or 4WD and 4H or 4LO. DTC P1813 will set if
more than two switch inputs are simultaneously detected by the transfer control unit due to a short circuit in the
4WD shift switch.
DTC LogicINFOID:0000000005148793
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE
1.DTC CONFIRMATION PROCEDURE
1. Turn ignition switch ON.
2. Perform self-diagnosis.
Is DTC P1813 displayed?
YES >> Perform diagnosis procedure. Refer to DLN-32, "Diagnosis Procedure".
NO >> Inspection End.
Diagnosis ProcedureINFOID:0000000005148794
Regarding Wiring Diagram information, refer to DLN-89, "Wiring Diagram - ALL-MODE 4WD SYSTEM -".
1.CHECK 4WD SHIFT SWITCH SIGNAL
With CONSULT-III
1. Turn ignition switch ON. (Do not start engine.)
2. Select DATA MONITOR mode for ALL MODE AWD/4WD with CONSULT-III.
3. Read out ON/OFF switching action of the 2WD SWITCH, AUTO SWITCH, LO CK SWITCH, 4L SW with
operating 4WD shift switch.
Without CONSULT-III1. Turn ignition switch ON. (Do not start engine.)
2. Check voltage between transfer control unit harness connector terminals and ground.
DTC CONSULT-III Diagnostic item is detected when... Reference
[P1813] 4WD MODE SW More than two switch inputs are simulta-
neously detected due to short circuit of
4WD shift switch.Refer to
DLN-32
.
Connector Terminal ConditionVoltage (Ap-
prox.)
E142 9 - ground
4WD shift switch: 2WD
Battery voltage
4WD shift switch: AUTO, 4H or 4LO 0V
18 - ground 4WD shift switch: 4H
Battery voltage
4WD shift switch: 2WD, AUTO or
4LO 0V
23 - ground 4WD shift switch: 4LO
Battery voltage
4WD shift switch: 2WD, AUTO or 4H 0V
24 - ground 4WD shift switch: AUTO
Battery voltage
4WD shift switch: 2WD, 4H or 4LO 0V
WDIA0148E
Revision: April 20092010 QX56

P1813 4WD SHIFT SWITCHDLN-33
< COMPONENT DIAGNOSIS > [ATX14B]
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Are inspection results normal?
YES >> GO TO 5.
NO >> GO TO 2.
2.CHECK 4WD SHIFT SWITCH POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF. (Stay for at least 5 seconds.)
2. Disconnect 4WD shift switch harness connector.
3. Check voltage between 4WD shift switch harness connector ter- minal 1 and ground.
4. Turn ignition switch ON. (Do not start engine.)
5. Check voltage between 4WD shift switch harness connector ter- minal 1 and ground.
Are inspection results normal?
YES >> GO TO 3.
NO >> Refer to DLN-22, "
Diagnosis Procedure".
3.CHECK HARNESS BETWEEN 4W D SHIFT SWITCH AND TRANSFER CONTROL UNIT
1. Turn ignition switch OFF. (Stay for at least 5 seconds.)
2. Disconnect transfer control unit harness connector and the 4WD shift switch harness connector.
3. Check continuity between the following terminals.
- Transfer control unit harness connector E142 terminal 9 and 4WD shift switch harness connector M141 terminal 2.
- Transfer control unit harness connector E142 terminal 18 and 4WD shift switch harness connector M141 terminal 5.
- Transfer control unit harness connector E142 terminal 23 and 4WD shift switch harness connector M141 terminal 6.
- Transfer control unit harness connector E142 terminal 24 and
4WD shift switch harness connector M141 terminal 3.
Also check harness for short to ground and short to power.
Are inspection results normal?
YES >> GO TO 4.
NO >> Check the following. If any items are damaged, repair or replace damaged parts. • Harness for short or open between battery and transfer shut off relay harness connector E69
terminal 5.
• Power supply circuit for trans fer control unit. Refer to DLN-22, "
Diagnosis Procedure".
4.CHECK 4WD SHIFT SWITCH
1. Turn ignition switch OFF. (Stay for at least 5 seconds.)
2. Disconnect 4WD shift switch harness connector.
Connector Terminal Voltage (Approx.)
M141 1 - Ground 0V
SDIA2383E
ConnectorTerminal Voltage (Approx.)
M141 1 - Ground Battery voltage
PDIA0210E
Continuity should exist.SDIA2699E
Revision: April 20092010 QX56

DLN-34
< COMPONENT DIAGNOSIS >[ATX14B]
P1813 4WD SHIFT SWITCH
3. Operate 4WD shift switch and check continuity between 4WD
shift switch terminals.
Are inspection results normal?
YES >> GO TO 5.
NO >> Replace 4WD shift switch.
5.CHECK TRANSFER CONTROL UNIT
Check transfer control unit input/output signal. Refer to DLN-81, "
Reference Value".
Are inspection results normal?
YES >> GO TO 6.
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.
6.CHECK DTC
Drive the vehicle and then perform self-diagnosis.
Are inspection results normal?
YES >> Inspection End.
NO >> Replace transfer control unit. Refer to DLN-130, "
Removal and Installation".
Component InspectionINFOID:0000000005148795
COMPONENT INSPECTION
1. Turn ignition switch OFF. (Stay for at least 5 second.)
2. Disconnect 4WD shift switch harness connector.
3. Operate 4WD shift switch and check continuity between 4WD
shift switch terminals.
Terminal ConditionContinuity
1 - 2 4WD shift switch: 2WD
Yes
4WD shift switch: AUTO, 4H and
4LO No
1 - 3 4WD shift switch: AUTO
Yes
4WD shift switch: 2WD, 4H and
4LO No
1 - 4 4WD shift switch: 2WD
No
4WD shift switch: AUTO, 4H and
4LO Ye s
1 - 5 4WD shift switch: 4H
Yes
4WD shift switch: 2WD, AUTO,
and 4LO No
1 - 6 4WD shift switch: 4LO
Yes
4WD shift switch: 2WD, AUTO and
4H No
WDIA0205E
Terminal
ConditionContinuity
1 - 2 4WD shift switch: 2WD
Yes
4WD shift switch: AUTO, 4H and
4LO No
1 - 3 4WD shift switch: AUTO
Yes
4WD shift switch: 2WD, 4H and
4LO No
WDIA0205E
Revision: April 20092010 QX56