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Home >> Nissan-Datsun >> 2004 >> Altima S, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 1182 (Engine Control System - DTCS P0222 To P0607 (VQ40DE)) >> DTC P0603: ECM Power Supply >> Diagnosis Procedure

Diagnosis Procedure

WARNING: This page is about a different car, the 2012 Nissan Pathfinder. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK ECM POWER SUPPLY
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check voltage between ECM terminal 121 and ground with CONSULT or tester.

    Voltage: Battery voltage 

    OK or NG 

    OK: GO TO  3.

    NG: GO TO 2.

    Fig 1: Checking Voltage Between ECM Terminal 121 And Ground Using Tester
    G08170673Courtesy of NISSAN NORTH AMERICA, INC.
  2. DETECT MALFUNCTIONING PART

    Check the following.

    • 20 A fuse(No. 53)
    • IPDM E/R harness connector E121
    • Harness for open or short between ECM and battery

    Repair open circuit in harness or connectors.

  3. CHECK INTERMITTENT INCIDENT

    Refer to "INTERMITTENT INCIDENT ".

    OK or NG 

    OK: GO TO 4.

    NG: Repair or replace harness or connectors.

  4. PERFORM DTC CONFIRMATION PROCEDURE

    With CONSULT 

    1. Turn ignition switch ON.
    2. Select "SELF DIAG RESULTS" mode with CONSULT.
    3. Touch "ERASE".
    4. Perform DTC Confirmation Procedure  .

      See "DTC CONFIRMATION PROCEDURE ".

    5. Is the 1st trip DTC P0603 displayed again? 

    With GST 

    1. Turn ignition switch ON.
    2. Select Service $04 with GST.
    3. Perform DTC Confirmation Procedure  .

      See "DTC CONFIRMATION PROCEDURE ".

    4. Is the 1st trip DTC P0603 displayed again?

    Yes or No 

    Yes: GO TO 5.

    No: INSPECTION END 

  5. REPLACE ECM
    1. Replace ECM.
    2. Perform initialization of NVIS(NATS) system and registration of all NVIS(NATS) ignition key IDs. Refer to "ADDITIONAL SERVICE WHEN REPLACING CONTROL UNIT: SPECIAL REPAIR REQUIREMENT " (with Intelligent Key system) or "ADDITIONAL SERVICE WHEN REPLACING CONTROL UNIT: SPECIAL REPAIR REQUIREMENT " (without Intelligent Key system).
    3. Perform "VIN REGISTRATION ".
    4. Perform "ACCELERATOR PEDAL RELEASED POSITION LEARNING ".
    5. Perform "THROTTLE VALVE CLOSED POSITION LEARNING ".
    6. Perform "IDLE AIR VOLUME LEARNING ".

    INSPECTION END