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ECM Power Source Circuit: Procedure

  1. INSPECT ECM (+B VOLTAGE) 
    1. Disconnect the E4 and E8 ECM connectors.
      Fig 1: Identifying E4 And E8 ECM Connectors
      GTY165335Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Turn the ignition switch to the ON position.
    3. Measure the voltage according to the value(s) in the table below.

      Standard voltage

      Tester Connection Specified Condition
      +B (E4-1) - E1 (E8-3) 11 to 14 V
    4. Reconnect the ECM connectors.

    OK → See step   8 

    NG: Go to next step 

  2. CHECK WIRE HARNESS (ECM - BODY GROUND) 
    1. Disconnect the negative battery cable.
      Fig 2: Identifying ECM Connector
      GTY165242Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the E8 ECM connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance

      Tester Connection Specified Condition
      E1 (E8-3) - Body ground Below 1 Ω
    4. Reconnect the cable.
    5. Reconnect the ECM connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  3. INSPECT ECM (IGSW VOLTAGE) 
    1. Disconnect the E4 and E8 ECM connectors.
      Fig 3: Identifying ECM Connector And IGSW
      GTY162298Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Turn the ignition switch to the ON position.
    3. Measure the voltage according to the value(s) in the table below.

      Standard voltage

      Tester Connection Specified Condition
      IGSW (E4-9) - E1 (E8-3) 11 to 14 V
    4. Reconnect the ECM connectors.

    OK → See step   5 

    NG: Go to next step 

  4. INSPECT IGNITION SWITCH ASSEMBLY 
    1. Disconnect the I5 ignition switch connector.
      Fig 4: Identifying AM2 And IG2 Terminal Of Ignition Switch Connector
      GTY161969Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance

      Switch Position Tester Connection Specified Condition
      LOCK All Terminals 10 kΩ or higher
      ON IG2 (6) - AM2 (7) Below 1 Ω
    3. Reconnect the ignition switch connector.

    NG → See step   9 

    OK → CHECK AND REPLACE HARNESS AND CONNECTOR (BATTERY - IGNITION SWITCH, IGNITION SWITCH - ECM) 

  5. INSPECT ECM (MREL VOLTAGE) 
    1. Turn the ignition switch to the ON position.
      Fig 5: Identifying MREL And E1 Terminal Of ECM Connector
      GTY164241Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the voltage according to the value(s) in the table below.

      Standard voltage

      Tester Connection Specified Condition
      MREL (E4-8) - E1 (E8-3) 11 to 14 V

    NG → See step   10 

    OK: Go to next step 

  6. INSPECT EFI RELAY 
    1. Remove the EFI relay from the engine room relay block.
      Fig 6: Inspecting EFI Relay
      GTY160741Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance

      Tester Connection Specified Condition
      3 - 5 10 kΩ or higher
      3 - 5 Below 1 Ω
      (when battery voltage is applied to terminals 1 and 2)
    3. Reinstall the EFI relay.

    NG → REPLACE EFI RELAY 

    OK: Go to next step 

  7. CHECK HARNESS AND CONNECTOR (EFI RELAY - ECM, BODY GROUND) 
    1. Check the wire harness between the EFI relay and ECM.
      Fig 7: Identifying EFI Relay And ECM Connector
      GTY165618Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      1. Remove the EFI relay from the engine room relay block.
      2. Disconnect the E4 ECM connector.
      3. Measure the resistance according to the value(s) in the table below.

        Standard resistance

        Tester Connection Specified Condition
        Engine room relay block (EFI relay terminal 1) - MREL (E4-8) Below 1 Ω
        Engine room relay block (EFI relay terminal 3) - +B (E4-1) Below 1 Ω
        Engine room relay block (EFI relay terminal 1) or MREL (E4-8) - Body ground 10 kΩ or higher
        Engine room relay block (EFI relay terminal 3) or +B (E4-1) - Body ground 10 kΩ or higher
      4. Reinstall the EFI relay.
      5. Reconnect the ECM connector.
    2. Check the wire harness between the EFI relay and body ground.
      1. Remove the EFI relay from the engine room relay block.
      2. Measure the resistance according to the value(s) in the table below.

        Standard resistance

        Tester Connection Specified Condition
        Engine room relay block (EFI relay terminal 2) - Body ground Below 1 Ω
      3. Reinstall the EFI relay.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK → CHECK AND REPAIR HARNESS AND CONNECTOR (TERMINAL 5 OF EFI RELAY - BATTERY POSITIVE TERMINAL) 

  8. PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE 
  9. REPLACE IGNITION SWITCH ASSEMBLY. Refer to  REMOVAL 
  10. REPLACE ECM. Refer to  REMOVAL 
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