Diagnosis Procedure

Regarding Wiring Diagram information, refer to "WIRING DIAGRAM ".

1. CHECK POWER SUPPLY
   1. Turn ignition switch "OFF". (Stay for at least 5 seconds.)
   2. Disconnect transfer control unit harness connector.
   3. Check voltage between transfer control unit harness connector terminals and ground.

      Connector	Terminal	Voltage (Approx.)
      M165	19 - Ground	Battery voltage
      	25 - Ground	0V
      M166	40 - Ground	Battery voltage
      	44 - Ground	0V
      	45 - Ground

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

      Courtesy of NISSAN NORTH AMERICA, INC.
   4. Turn ignition switch "ON". (Do not start engine.)
   5. Check voltage between transfer control unit harness connector terminals and ground.

      Connector	Terminal	Voltage (Approx.)
      M165	19 - Ground	Battery voltage
      	25 - Ground
      M166	40 - Ground
      	44 - Ground
      	45 - Ground

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

      Courtesy of NISSAN NORTH AMERICA, INC.

      Is there voltage? 

      YES: GO TO 2.

      NO: Check the following. If any items are damaged, repair or replace damaged parts.

      • 40A fuse (No. j, located in the fuse and fusible link box).
      • 10A fuses (No. 18, located in the fuse block (J/B) and Nos. 60 and 61 located in the fuse and relay box).
      • Harness for short or open between battery and transfer control unit harness connector M165 terminal 19.
      • Harness for short or open between battery and transfer shut off relay 2 harness connector E157 terminal 1 and 3.
      • Harness for short or open between battery and transfer shut off relay 1 harness connector E156 terminal 3.
      • Harness for short or open between ignition switch and transfer control unit harness connector M165 terminal 25.
      • Harness for short or open between ignition switch and transfer shut off relay 1 harness connector E156 terminal 1.
      • Harness for short or open between transfer shut off relay 2 harness connector E157 terminal 5 and transfer control unit harness connector M166 terminals 44, 45.
      • Harness for short or open between transfer shut off relay 1 harness connector E156 terminal 5 and transfer control unit harness connector M166 terminals 44, 45.
      • Harness for short or open between transfer shut off relay 2 harness connector E157 terminal 2 and transfer control unit harness connector M166 terminal 40.
      • Harness for open between transfer shut off relay 1 harness connector E156 terminal 2 and ground.
      • Battery and ignition switch.
      • Transfer shut off relay 1, 2. Refer to "COMPONENT INSPECTION ".
2. CHECK GROUND CIRCUIT
   1. Turn ignition switch "OFF".
   2. Disconnect transfer control unit harness connector.
   3. Check continuity between transfer control unit harness connector M165 terminals 6 and 18, and M166 terminal 32 and ground.

      Continuity should exist  .

      Fig 3: Checking Continuity Between Transfer Control Unit Harness Connector M165 Terminals 6 And 18 And M166 Terminal 32 And Ground

      Courtesy of NISSAN NORTH AMERICA, INC.

      Also check harness for short to power.

      Do you have continuity? 

      YES: GO TO 3.

      NO: Repair open circuit or short to power in harness or connectors.

3. CHECK TRANSFER CONTROL UNIT

   Check transfer control unit input/output signal. Refer to "REFERENCE VALUE ".

   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

   Drive vehicle and then perform Self-diagnosis.

   Do DTCs P1801 or P1811 display? 

   YES: Replace transfer control unit. Refer to "REMOVAL AND INSTALLATION ".

   NO: Inspection End.