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Home >> Infiniti >> 2012 >> QX56 AWD >> Repair and Diagnosis >> Steering >> Power Steering >> Steering Control System >> DTC/Circuit Diagnosis >> Engine Speed Signal Circuit >> Diagnosis Procedure

Diagnosis Procedure

  1. PERFORM ECM SELF-DIAGNOSIS

    With CONSULT 

    Perform "ENGINE" self-diagnosis.

    Is any DTC detected? 

    YES: Check the DTC. Refer to "DTC INDEX ".

    NO: GO TO 2.

  2. CHECK HARNESS BETWEEN ECM AND POWER STEERING CONTROL UNIT
    1. Turn the ignition switch OFF.
    2. Disconnect ECM harness connectors.
    3. Disconnect power steering control unit harness connector.
    4. Check the continuity between ECM harness connector and power steering control unit harness connector.
      ECM Power steering control unit Continuity
      Connector Terminal Connector Terminal
      E80 169 M108 10 Existed
    5. Check the continuity between power steering control unit harness connector and ground.
      Power steering control unit - Continuity
      Connector Terminal
      M108 10 Ground Not existed

      Is the inspection result normal? 

      YES: GO TO 3.

      NO: Repair or replace error-detected parts.

  3. CHECK ENGINE SPEED SIGNAL (ECM)
    1. Connect ECM harness connectors.
    2. Check the signal between ECM harness connector and ground with oscilloscope.
      ECM - Condition Voltage (Approx.)
      Connector Terminal
      E80 169 Ground Engine is running
      • Warm-up condition
      • Idle speed
      G07021891
      Engine is running
      • Warm-up condition
      • Engine speed: Approx. 2, 000 rpm
      G07020375

      Is the inspection result normal? 

      YES: GO TO 4.

      NO: Replace ECM. Refer to "DESCRIPTION ".

  4. CHECK ENGINE SPEED SIGNAL (POWER STEERING CONTROL UNIT)
    1. Turn the ignition switch OFF.
    2. Connect power steering control unit harness connector.
    3. Check the signal between power steering control unit harness connector and ground with oscilloscope.
      Power steering control unit - Condition Voltage (Approx.)
      Connector Terminal
      M108 10 Ground Engine is running
      • Warm-up condition
      • Idle speed
      G07021891
      Engine is running
      • Warm-up condition
      • Engine speed: Approx. 2, 000 rpm
      G07020375

      Is the inspection result normal? 

      YES: GO TO 5.

      NO: Replace power steering control unit. Refer to "REMOVAL AND INSTALLATION ".

  5. CHECK TERMINALS AND HARNESS CONNECTORS
    • Check the power steering control unit pin terminals for damage or loose connection with harness connector.
    • Check the ECM pin terminals for damage or loose connection with harness connector.

      Is the inspection result normal? 

      YES: INSPECTION END

      NO: Repair or replace error-detected parts.

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