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Home >> Infiniti >> 2004 >> QX56 RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1208 (Transfer Case) >> Trouble Diagnosis For System >> Power Supply Circuit For Transfer Control Unit >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2005 Infiniti QX56. However, it is still accessible from the selected car via links, so may be relevant.
  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.
      Fig 1: Transfer Control Unit Harness Connector Terminals And Ground Voltage Specifications
      G02382972Courtesy of NISSAN MOTOR CO., U.S.A.
      Fig 2: Checking Voltage Between Transfer Control Unit Harness Connector Terminals And Ground
      G02382973Courtesy of NISSAN MOTOR CO., U.S.A.
    4. Turn ignition switch "ON". (Do not start engine.)
    5. Check voltage between transfer control unit harness connector terminals and ground.
      Fig 3: Transfer Control Unit Harness Connector Terminals And Ground Voltage Specifications
      G02382974Courtesy of NISSAN MOTOR CO., U.S.A.
      Fig 4: Checking Voltage Between Transfer Control Unit Harness Connector Terminals And Ground
      G02382975Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK: GO TO 2.
    2. NG: 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. Refer to "POWER SUPPLY ROUTING CIRCUIT ".
      • 20A fuse No. 53 located in the IPDM E/R. Refer to "POWER SUPPLY ROUTING CIRCUIT ".
      • 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 (G), and 3 (G).
      • Harness for short or open between transfer shut off relay harness connector E69 terminal 2 (SB) and transfer control unit harness connector terminal 30.
      • Harness for short or open between transfer shut off relay harness connector E69 terminal 5 (Y/R) and transfer control unit harness connector terminals 16 (Y/R) and 22 (Y/R).
      • Battery and ignition switch. Refer to "POWER SUPPLY ROUTING CIRCUIT ".
      • Transfer shut off relay. Refer to "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 connector E142 terminals 3 (B), 6 (B), E143 terminal 45 (B) and ground.
      1. Continuity should exist. 

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

    OK or NG 

    1. OK: GO TO 3.
    2. NG: Repair open circuit or short to ground or short to power in harness or connectors.
    Fig 5: Checking Continuity Between Transfer Control Unit Harness Connector E142 Terminals 3, 6 And E143 Terminal 45 And Ground
    G02382976Courtesy of NISSAN MOTOR CO., U.S.A.
  3. CHECK TRANSFER CONTROL UNIT 

    Check transfer control unit input/output signal. Refer to "TRANSFER CONTROL UNIT INPUT/OUTPUT SIGNAL REFERENCE VALUES ".

    OK or NG 

    1. OK: GO TO 4.
    2. 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.
  4. CHECK DTC 

    Perform the self-diagnosis, after driving a vehicle for a while.

    OK or NG 

    1. OK: Inspection End.
    2. NG: Replace transfer control unit. Refer to "REMOVAL AND INSTALLATION ".
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