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Test Dc: Mass Airflow Sensor: Testing

    NOTE: For additional testing information, see DIAGNOSTIC AIDS .
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 1) to step 10). No test procedures have been omitted.

  1. 1) DTC P0100: Check MAF Signal To PCM
    DTC P0100 indicates signal received by PCM is an excessively high voltage during KOEO, high voltage during light load driving conditions, excessively low voltage during KOER, or low voltage during heavy load driving conditions. When DTC P0100 is detected, PCM enters fail safe mode, MIL is illuminated, and engine speed will not rise more than 2400 RPM due to fuel cut. Possible causes are as follows:
    • MAF circuit open, or short to GND or VPWR.
    • MAF RTN circuit open, or short to GND or VPWR.
    • Faulty MAF sensor
    • Air intake leak.
    • PWR GND circuit open.
    • VPWR circuit open or short to GND.

    Turn ignition off. Check air intake system for leaks. Connect scan tool to DLC. Ensure engine is at normal operating temperature. Start engine and allow to idle. Using scan tool, access MAF PID from PID/DATA MONITOR & RECORD menu. If MAF PID reading is 1.0-1.7 volt, leave scan tool connected and go to step  30). If MAF PID reading is one volt or less, go to step  10). If MAF PID reading is more than 1.7 volt, go to step  20).

  2. 10) Check VPWR Voltage To MAF

    Turn ignition off. Disconnect MAF sensor harness connector. Turn ignition on. Using DVOM, measure voltage between chassis ground and VPWR circuit at MAF sensor harness connector. See Figure. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, go to TEST B  , step  1).

  3. 11) Check MAF Circuit For Short To Ground

    Ensure ignition is off. Ensure MAF sensor is disconnected. Disconnect PCM harness connector. Inspect connector for damaged pins and repair if necessary. Using DVOM, measure resistance between MAF, MAF REF and GND circuits at PCM harness connector. See PCM TERMINAL CIRCUIT IDENTIFICATION  and MAF SENSOR CIRCUIT IDENTIFICATION  tables. If all resistances are more than 10 k/ohms, go to next step. If any resistance is 10 k/ohms or less, repair short between affected circuits. See WIRING DIAGRAMS article.

  4. 12) Check MAF Sensor Harness

    Ensure MAF sensor and PCM are disconnected. Using DVOM, measure resistance of MAF and MAF REF circuits between MAF sensor harness connector and PCM harness connector. See Figure and Figure . If both resistances are less than 5 ohms, go to next step. If either resistance is 5 ohms or more, repair open in affected circuit.

  5. 13) Check PCM

    Reconnect PCM harness connector. Start engine and allow it to idle. Using scan tool, access MAF PID from PID/DATA MONITOR & RECORD menu. Check MAF PID at idle and at 2000 RPM. If MAF PID value is less than one volt, replace PCM. If MAF PID value is one volt or more, replace MAF sensor.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 13) to step 20). No test procedures have been omitted.

  6. 20) Check MAF Circuit For Short To Power

    Turn ignition off. Disconnect PCM and MAF sensor harness connectors. Using DVOM, measure resistance between MAF, MAF REF and VPWR circuits at PCM harness connector. See Figure and Figure . If resistances are more than 10 k/ohms, replace MAF sensor. If any resistance is 10 k/ohms or less, repair short between affected circuits. See WIRING DIAGRAMS article.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 20) to step 30). No test procedures have been omitted.

  7. 30) MAF Sensor Performance Check

    Turn ignition off. Using scan tool, access MAF PID from PID/DATA MONITOR & RECORD menu. Start engine and operate at specified RPM. See MAF SENSOR PERFORMANCE  table. If MAF PID values are not within voltage specifications listed, replace MAF sensor. If MAF PID values are within voltage specifications listed, fault may be intermittent. Go to TEST Z  , step  1), or go to INTERMITTENTS in TROUBLE SHOOTING - NO CODES - VILLAGER article.
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