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Mass Airflow Sensor

  1. Turn ignition on. Using voltmeter, backprobe ECU connector terminal B5 (White wire). If voltage is greater than 0.3 volt, check White wire between MAF sensor and ECU terminal B5 for short to voltage. If wire is okay, temporarily substitute known good ECU. Retest system.
  2. Using voltmeter, backprobe ECU connector terminal C1 (Black/Blue wire). If voltage is greater than zero volts, check Black/Blue wire between Mass Airflow (MAF) sensor and ECU terminal C1 for short to voltage. If wire is okay, temporarily substitute known good ECU. Retest system.
  3. Start and idle engine. Using voltmeter, backprobe ECU connector terminal B5 (White wire). If voltage is not 0.8-1.2 volts, repair White wire between MAF sensor and ECU terminal B5.
  4. Using voltmeter, backprobe ECU connector terminal C1 (Black/Blue wire). If voltage exists, check Black/Blue wire between MAF sensor and ECU terminal C1 for short to voltage. If wire is okay, temporarily substitute known good ECU. Retest system.
  5. Turn ignition off. Unplug connector from MAF sensor. Turn ignition on. Check for battery voltage at MAF sensor connector terminal No. 1 (Yellow/Green wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair Yellow/Green wire from main relay. See WIRING DIAGRAMS article.
  6. Turn ignition off. Unplug connectors from ECU. Check Black/Blue, White, and Black/Red wires between MAF sensor and ECU for shorts or opens. Repair as necessary.
  7. If all wires are okay, temporarily substitute known good MAF sensor. Retest system. If system still malfunctions, temporarily substitute known good ECU. Retest system.
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