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Home >> Scion >> 2004 >> xA Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Diagnosis >> DTC P0100, DTC P0102, DTC P0103: Mass Or Volume Air Flow Circuit >> Inspection Procedure

Inspection Procedure

NOTE: Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.
  1. READ VALUE OF HAND-HELD TESTER OR OBD II SCAN TOOL (MASS AIR FLOW RATE) 
    1. Connect the hand-held tester or the OBD II scan tool to the DLC3.
    2. Start the engine.
    3. Push the hand-held tester or the OBD II scan tool main switch ON.
    4. Select the item "DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL / MAF" and read its value displayed on the hand-held tester or the OBD II scan tool.

      Result: 

      RESULT

      Air Flow Rate (gm/s) Proceed to
      0.0 A
      271.0 or more B
      Between 1.0 and 270.0 ((1)) C
      (1) The value must be changed when the throttle valve is opened or closed.
    1. B : Go to step   6 . 
    2. C : CHECK FOR INTERMITTENT PROBLEMS (See  CHECK FOR INTERMITTENT PROBLEMS  ) 
    3. A : Go to next step. 
  2. INSPECT MASS AIR FLOW SENSOR (POWER SOURCE) 
    1. Turn the ignition switch ON.
    2. Disconnect the M1 mass air flow sensor connector.
      3. Fig 1: Disconnecting M1 Mass Air Flow Sensor Connector
      G03367018Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    3. Measure the voltage between the terminal of the wire harness side connector and body ground.

      Standard: 

      STANDARD

      Tester Connection Specified Condition
      +B (M1-1) - Body Ground 9 to 14 V
    4. Reconnect the mass air flow sensor connector.
    1. NG : Go to step   5 . 
    2. OK : Go to next step. 
  3. INSPECT ECM (VG VOLTAGE) 
    1. Start the engine.
    2. Measure the voltage between the specified terminals of the E4 ECM connector.
      Fig 2: Measuring Voltage Between Specified Terminals Of E4 ECM Connector
      G03367019Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      NOTE: The shift position should be P or N and the A/C switch should be turned OFF.

      Standard: 

      STANDARD

      Tester Connection Condition Specified Condition
      VG (E4-24) - EVG (E4-32) Engine Is Idling 0.5 to 3.0 V
    1. OK : REPLACE ECM (See  REPLACEMENT  ) 
    2. NG : Go to next step. 
  4. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW SENSOR - ECM) 
    1. Disconnect the M1 mass air flow sensor connector.
      2. Fig 3: Disconnecting M1 Mass Air Flow Sensor Connector
      G03367020Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the E4 ECM connector.
    3. Measure the resistance between the wire harness side connectors.

      Standard (Check for open): 

      CHECK HARNESS AND CONNECTOR

      Tester Connection Specified Condition
      VG (M1-3) - VG (E4-24) Below 1 Ω
      E2G (M1-2) - EVG (E4-32)

      Standard (Check for short): 

      STANDARD (CHECK FOR SHORT)

      Tester Connection Specified Condition
      VG (M1-3) or VG (E4-24) - Body Ground 10 kΩ or higher
    4. Reconnect the mass air flow sensor connector.
      5. Fig 4: Connecting Mass Air Flow Sensor Connector
      G03367021Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    5. Reconnect the ECM connector.
    1. NG : REPAIR OR REPLACE HARNESS OR CONNECTOR 
    2. OK : REPLACE MASS AIR FLOW SENSOR 
  5. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW SENSOR - EFI RELAY) 
    1. Remove the EFI relay from the engine room R/B.
      2. Fig 5: Removing EFI Relay From Engine Room R/B
      G03367022Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the M1 mass air flow sensor connector.
    3. Measure the resistance between the wire harness side connectors.

      Standard (Check for open): 

      STANDARD (CHECK FOR OPEN)

      Tester Connection Specified Condition
      +B (M1-1) - EFI Relay (3) Below 1 Ω

      Standard (Check for short): 

      STANDARD (CHECK FOR SHORT)

      Tester Connection Specified Condition
      +B (M1-1) or EFI relay (3) - Body Ground 10 kΩ or higher
    4. Reconnect the mass air flow sensor connector.
      5. Fig 6: Connecting Mass Air Flow Sensor Connector
      G03367023Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    5. Reinstall the EFI relay.
    1. NG : REPAIR OR REPLACE HARNESS OR CONNECTOR 
    2. OK : CHECK FOR ECM POWER SOURCE CIRCUIT (See  ECM POWER SOURCE CIRCUIT  ) 
  6. INSPECT ECM (SENSOR GROUND) 
    1. Check the resistance between the specified terminal of the E4 ECM connector and the body ground.
      Fig 7: Checking Resistance Between Specified Terminal Of E4 ECM Connector & Body Ground
      G03367024Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard: 

      STANDARD

      Tester Connection Specified Condition
      EVG (E4-32) - Body Ground Below 1 Ω
    1. NG : REPLACE ECM (See  REPLACEMENT  ) 
    2. OK : Go to next step. 
  7. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW SENSOR - ECM) 
    1. Disconnect the M1 mass air flow sensor connector.
      2. Fig 8: Disconnecting M1 Mass Air Flow Sensor Connector
      G03367025Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the E4 ECM connector.
    3. Measure the resistance between the wire harness side connectors.

      Standard (Check for open): 

      STANDARD (CHECK FOR OPEN)

      Tester Connection Specified Condition
      VG (M1-3) - VG (E4-24) Below 1 Ω
      E2G (M1-2) - EVG (E4-32)

      Standard (Check for short): 

      STANDARD (CHECK FOR SHORT)

      Tester Connection Specified Condition
      VG (M1-3) or VG (E4-24) - Body Ground 10 kΩ or higher
    4. Reconnect the mass air flow sensor connector.
      5. Fig 9: Connecting Mass Air Flow Sensor Connector
      G03367026Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    5. Reconnect the ECM connector.
    1. NG : REPAIR OR REPLACE HARNESS OR CONNECTOR 
    2. OK : REPLACE MASS AIR FLOW SENSOR 
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