LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 2009 >> IS 250 AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (DTCS P0420 - U0101 & Circuit Tests) >> SFI System >> MIL Circuit >> Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

MIL Circuit: Procedure

  1. CHECK WHETHER MIL TURN OFF 
    1. Connect Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the tester on.
    4. Check whether any DTCs have been stored. Refer to DTC CHECK / CLEAR . Note them down if necessary.
    5. Clear DTCs. Refer to DTC CHECK / CLEAR .
    6. Check if the MIL turns off.

      OK

      MIL turns off.

    OK → REPAIR CIRCUITS INDICATED BY OUTPUT DTCS 

    NG: Go to next step 

  2. CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT IN WIRE HARNESS) 
    1. Disconnect the A6 ECM connector.
      Fig 1: Identifying A6 ECM Connector
      GTY137150Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Turn the engine switch on (IG).
    3. Check the MIL is not illuminated.

      OK

      MIL is not illuminated.

    4. Reconnect the ECM connector.

    OK → REPLACE ECM 

    NG: Go to next step 

  3. CHECK HARNESS AND CONNECTOR (COMBINATION METER - ECM) 
    1. Disconnect the A6 ECM connector.
      Fig 2: Identifying J35 Combination Meter Connector And A6 ECM Connector
      GTY143147Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the J35 combination meter connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance (Check for open)

      Tester Connection Specified Condition
      W (A6-8) - EFI (J35-12) Below 1 Ω

      Standard resistance (Check for short)

      Tester Connection Specified Condition
      W (A6-8) or EFI (J35-12) - Body ground 10 kΩ or higher
    4. Reconnect the connectors.

    OK → REPAIR OR REPLACE COMBINATION METER ASSEMBLY 

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

  4. CHECK THAT MIL IS ILLUMINATED 
    1. Check if the MIL is illuminated when the engine switch is turns on (IG).

      OK

      MIL is illuminated.

    OK → END 

    NG: Go to next step 

  5. CHECK HARNESS AND CONNECTOR 
    1. Disconnect the A6 ECM connector.
      Fig 3: Identifying A6 ECM Connector
      GTY137150Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Turn the engine switch on (IG).
    3. Measure the voltage according to the value(s) in the table below.

      Standard voltage

      Tester Connection Specified Condition
      W (A6-8) - Body ground 10 to 14 V
    4. Reconnect the ECM connector.

    OK → REPLACE ECM 

    NG: Go to next step 

  6. CHECK HARNESS AND CONNECTOR (COMBINATION METER - ECM) 
    1. Disconnect the A6 ECM connector.
      Fig 4: Identifying J35 Combination Meter Connector And A6 ECM Connector
      GTY143147Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the J35 combination meter connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance (Check for open)

      Tester Connection Specified Condition
      W (A6-8) - EFI (J35-12) Below 1 Ω

      Standard resistance (Check for short)

      Tester Connection Specified Condition
      W (A6-8) or EFI (J35-12) - Body ground 10 kΩ or higher
    4. Reconnect the connectors.

    OK → REPAIR OR REPLACE COMBINATION METER ASSEMBLY 

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

scientia non olet · About LEMON Manuals