Infiniti QX56 (JA60). Manual - part 275

P1811 POWER SUPPLY CIRCUIT FOR TRANSFER CONTROL UNIT

DLN-23

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Are the inspection results normal?

YES

>> GO TO 2.

NO

>> Check the following. If any items are damaged, repair or replace damaged parts.

• 10A fuses No. 26 located in fuse and fusible link box and No. 59 located in the fuse and relay

box.

• 20A fuse No. 53 located in the IPDM E/R.

• Harness for short or open between battery and transfer control unit harness connector terminals

47.

• Harness for short or open between battery and transfer control unit harness connector terminal

29.

• Harness for short or open between battery and transfer shut off relay harness connector E69

terminal 1, and 5.

• Harness for short or open between transfer shut off relay harness connector E69 terminal 2  and

transfer control unit harness connector terminal 30.

• Harness for short or open between transfer shut off relay harness connector E69 terminal 3  and

transfer control unit harness connector terminals 16 and 22.

• Battery and ignition switch.

• Transfer shut off relay. Refer to 

DLN-23, "Component Inspection"

.

2.

CHECK GROUND CIRCUIT

1. Turn ignition switch OFF. (Stay for at least 5 seconds.)

2. Disconnect transfer control unit harness connector.

3. Check continuity between transfer control unit harness connec-

tor E142 terminals 3, 6, E143 terminal 45 and ground.

Also check harness for short to ground and short to power.

Are the inspection results normal?

YES

>> GO TO 3.

NO

>> Repair open circuit or short to ground or short to power

in harness or connectors.

3.

CHECK TRANSFER CONTROL UNIT

Check transfer control unit input/output signal. Refer to 

DLN-81, "Reference Value"

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Are the inspection results normal?

YES

>> GO TO 4.

NO

>> Check transfer control unit pin terminals for damage or loose connection with harness connector.

If any items are damaged, repair or replace damaged parts.

4.

CHECK DTC

Perform the self-diagnosis, after driving a vehicle for a while.
Are the inspection results normal?

YES

>> Inspection End.

NO

>> Replace transfer control unit. Refer to 

DLN-130, "Removal and Installation"

.

Component Inspection

INFOID:0000000005148778

1. Turn ignition switch OFF. (Stay for at least 5 seconds.)
2. Remove transfer shut off relay. Refer to 

DLN-16, "Component Parts Location"

.

Continuity should exist.

SDIA2691E

DLN-24

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P1811 POWER SUPPLY CIRCUIT FOR TRANSFER CONTROL UNIT

3. Apply 12V direct current between transfer shut off relay termi-

nals 1 and 2.

4. Check continuity between relay terminals 3 and 5.

5. If inspection results are abnormal replace the transfer shut off

relay.

Condition

Continuity

12V direct current supply between terminals 1 and 2

Yes

OFF

No

SCIA1245E

P1802 – P1804, P1809 TRANSFER CONTROL UNIT

DLN-25

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P1802 – P1804, P1809 TRANSFER CONTROL UNIT

Description

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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 set 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 Logic

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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 Procedure

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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)

DTC

CONSULT-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.

DLN-26

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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.