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Home >> Infiniti >> 2008 >> QX56 AWD >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Engine Control System - DTCS U1000 To P0308 >> DTC P0117, P0118: ECT Sensor >> Diagnosis Procedure
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Diagnosis Procedure

  1. CHECK GROUND CONNECTIONS
    1. Turn ignition switch OFF.
    2. Loosen and retighten three ground screws on the body.

      Refer to "GROUND INSPECTION ".

      Fig 1: Identifying Body Ground Screw
      G05739368Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    OK: GO TO 2.

    NG: Repair or replace ground connections.

  2. CHECK ECT SENSOR POWER SUPPLY CIRCUIT
    1. Disconnect engine coolant temperature (ECT) sensor (1) harness connector.
      Fig 2: Identifying Engine Coolant Temperature Sensor And Rocker Cover RH
      G05739369Courtesy of NISSAN MOTOR CO., U.S.A.
    2. Turn ignition switch ON.
    3. Check voltage between ECT sensor (1) terminal 1 and ground with CONSULT-III or tester.

      Voltage: Approximately 5V 

      Fig 3: Checking Voltage Between ECT Sensor Terminal 1 And Ground
      G05739370Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    OK: GO TO  4.

    NG: GO TO 3.

  3. DETECT MALFUNCTIONING PART

    Check the following.

    • Harness connector F26, F101
    • Harness for open or short between ECM and engine coolant temperature sensor

    Repair open circuit or short to ground or short to power in harness or connectors.

  4. CHECK ECT SENSOR GROUND CIRCUIT FOR OPEN AND SHORT
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check harness continuity between ECT sensor terminal 2 and ECM terminal 67.

      Refer to WIRING DIAGRAM .

      Continuity should exist. 

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

    OK or NG 

    OK: GO TO  6.

    NG: GO TO 5.

  5. DETECT MALFUNCTIONING PART

    Check the following.

    • Harness connector F26, F101
    • Harness for open and short between ECT sensor and ECM

    Repair open circuit or short to ground or short to power in harness or connectors.

  6. CHECK ENGINE COOLANT TEMPERATURE SENSOR

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    OK: GO TO 7.

    NG: Replace engine coolant temperature sensor.

  7. CHECK INTERMITTENT INCIDENT

    Refer to "HOW TO CHECK TERMINAL " and "INTERMITTENT INCIDENT ".

    INSPECTION END