Diagnostic Procedure

WARNING: This page is about a different car, the 2006 Nissan Titan. However, it is still accessible from the selected car via links, so may be relevant.

CHECK POWER SUPPLY

Turn ignition switch "OFF". (Stay for at least 5 seconds.)
Disconnect transfer control unit harness connector.

Check voltage between transfer control unit harness connector terminals and ground.

Fig 1: Checking Voltage Between Transfer Control Unit Harness Connector Terminals And Ground

Courtesy of NISSAN MOTOR CO., U.S.A.

TERMINALS VOLTAGE REFERENCE

Connector	Terminal	Voltage (Approx.)
E142	19 - Ground	Battery voltage
E142	25 - Ground	0V
E143	40 - Ground	Battery voltage
	44 - Ground	0V
	5 - Ground	0V

Turn ignition switch "ON". (Do not start engine.)

Check voltage between transfer control unit harness connector terminals and ground.

Fig 2: Checking Voltage Between Transfer Control Unit Harness Connector Terminals And Ground

Courtesy of NISSAN MOTOR CO., U.S.A.

TERMINALS VOLTAGE REFERENCE

Connector	Terminal	Voltage (Approx.)
E142	19 - Ground	Battery voltage
E142	25 - Ground
E143	40 - Ground
	44 - Ground
	45 - Ground

OK or NG

OK: GO TO 2.

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

10A fuses [No. 26 located in the fuse and fusible link box or 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 E142 terminal 19.
Harness for short or open between battery and transfer shut off relay 2 harness connector E47 terminal 1 and 5.
Harness for short or open between battery and transfer shut off relay 1 harness connector E46 terminal 5.
Harness for short or open between ignition switch and transfer control unit harness connector E142 terminal 25.
Harness for short or open between ignition switch and transfer shut off relay 1 harness connector E46 terminal 2.
Harness for short or open between transfer shut off relay 2 harness connector E47 terminal 3 and transfer control unit harness connector E143 terminals 44, 45.
Harness for short or open between transfer shut off relay 1 harness connector E46 terminal 3 and transfer control unit harness connector E143 terminals 44, 45.
Harness for short or open between transfer shut off relay 2 harness connector E47 terminal 2 and transfer control unit harness connector E143 terminal 40.
Harness for open between transfer shut off relay 1 harness connector E46 terminal 1 and ground.
Battery and ignition switch. Refer to "POWER SUPPLY ROUTING CIRCUIT ".
Transfer shut off relay 1, 2. Refer to "COMPONENT INSPECTION ".

CHECK GROUND CIRCUIT
1. Turn ignition switch "OFF".
2. Disconnect transfer control unit harness connector.
3. Check continuity between transfer control unit harness connector E142 terminals 6 and 18, and E143 terminal 32 and ground.
  Continuity should exist.
  
  Fig 3: Checking Continuity Between Transfer Control Unit Connector E142 Terminals 6 And 18, And E143 Terminal 32 And Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
  
  Also check harness for short to power.
OK or NG

OK: GO TO 3.

NG: Repair open circuit or short to power in harness or connectors.
CHECK TRANSFER CONTROL UNIT
Check transfer control unit input/output signal. Refer to "TRANSFER CONTROL UNIT INPUT/OUTPUT SIGNAL REFERENCE VALUES ".

OK or NG

OK: GO TO 4.

NG: Check transfer control unit pin terminals for damage or loose connection with harness connector. If any items are damaged, repair or replace damaged parts.
CHECK DTC
Perform the self-diagnosis, after driving a vehicle for a while.

OK or NG

OK: Inspection End.

NG: Replace transfer control unit. Refer to "TRANSFER CONTROL UNIT ".