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Diagnostic Procedure

WARNING: This page is about a different car, the 2003 Nissan Pathfinder. However, it is still accessible from the selected car via links, so may be relevant.
  1. If malfunction "A" was duplicated, go to next step. If malfunction "B" was duplicated, check for disconnected, kinked, clogged or obstructed air intake ducts. Check vacuum hoses for leaks, kinks, bends, cracks or oil fouling. If problem is found, repair as necessary. If no problem is found, go to next step.
  2. Turn ignition off. Loosen and retighten 2 engine ground bolts. See Fig 1. Disconnect MAF sensor 5-pin harness connector. See Fig 2. Turn ignition on. Measure voltage between ground and specified MAF sensor harness connector terminals. See MASS AIRFLOW SENSOR SUPPLY VOLTAGE table. See Fig 3. If voltage is as specified, go to step  4. If voltage is not as specified, go to next step.
    MASS AIRFLOW SENSOR SUPPLY VOLTAGE

    MAF Sensor Harness Connector Terminal No. Specification (Volts)
    2 About 5
    4 Battery Voltage
  3. Check the following:
    • Check for open or short between MAF sensor and ECM relay. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
    • Check for open or short between MAF sensor and ECM.
    If problem is found, repair as necessary. If no problem is found, go to next step.
  4. Turn ignition off. Disconnect ECM 116-pin harness connector. ECM is located behind instrument panel lower cover. See Figure. Check continuity of Black/Pink wire between MAF sensor harness connector terminal No. 3 and ECM harness connector terminal No. 67. See Figure and Fig 3 . Continuity should exist. Also, check circuit for short to voltage. If problem is found, repair as necessary. If no problem is found, leave harness connectors disconnected and go to next step.
  5. Check continuity of Orange wire between MAF sensor harness connector terminal No. 5 and ECM harness connector terminal No. 51. Continuity should exist. Also, check circuit for short to ground or short to voltage. If problem is found, repair as necessary. If no problem is found, connect all harness connectors and go to next step.
    6. CAUTION: DO NOT use ECM ground terminals when measuring voltage.
  6. Start engine and warm to normal operating temperature. Backprobing, measure voltage between ground and ECM harness connector terminal No. 51 (Orange wire), with engine at specified speeds. See MASS AIRFLOW SENSOR OUTPUT VOLTAGE  table. If voltage is as specified, go to next step. If voltage is not as specified, disconnect and reconnect MAF sensor harness connector and repeat test. If voltage is still not as specified, replace MAF sensor.
    MASS AIRFLOW SENSOR OUTPUT VOLTAGE

    Condition Volts
    Key On, Engine Off About 1.0
    Engine Idling 1.2-1.8
    2500 RPM 1.6-2.2
    Idle To 4000 RPM (1) 1.2-1.8 To About 4.0
    (1) Voltage should increase in proportion to engine speed.
  7. No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
Fig 1: Locating Engine Ground Bolts
G00103795Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 2: Locating Mass Airflow Sensor
G00025053Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 3: Identifying Mass Airflow Sensor Harness Connector Terminals
G99A52795Courtesy of NISSAN MOTOR CO., U.S.A.
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