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Home >> Toyota >> 2012 >> Prius Four >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System (Except Plug-In) (Diagnostic Codes (P0441-U0293) & Circuit Tests) >> SFI System >> Circuit Tests >> ECM Power Source Circuit >> Procedure
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ECM Power Source Circuit: Procedure

  1. CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND) 
    1. Disconnect the ECM connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      D28-104 (E1) - Body ground Always Below 1 Ω

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  2. INSPECT ECM (IGSW VOLTAGE) 
    1. Disconnect the ECM connector.
      Fig 1: Identifying Inspect ECM (IGSW Voltage)
      GTY290028Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Turn the power switch on (IG).
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      A57-28 (IGSW) - Body ground Power switch on (IG) 11 to 14 V
      TEXT IN ILLUSTRATION

      *a Front view of wire harness connector
      (to ECM)

    NG → See step   8 

    OK: Go to next step 

  3. INSPECT INTEGRATION RELAY (EFI MAIN RELAY) 
    1. Inspect the integration relay. Refer to INSPECTION .

    NG → See step   14 

    OK: Go to next step 

  4. CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY (EFI MAIN RELAY) - ECM) 
    1. Remove the integration relay from the engine room relay block.
    2. Disconnect the integration relay connector.
    3. Disconnect the ECM connector.
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)

      Tester Connection Condition Specified Condition
      1B-4 - A57-1 (+B2) Always Below 1 Ω
      1B-4 - A57-2 (+B) Always Below 1 Ω
      1B-2 - A57-6 (MREL) Always Below 1 Ω

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  5. CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY (EFI MAIN RELAY) - AUXILIARY BATTERY) 
    1. Remove the integration relay from the engine room relay block.
    2. Disconnect the integration relay connector.
    3. Disconnect the negative (-) auxiliary battery terminal.
    4. Disconnect the positive (+) auxiliary battery terminal.
    5. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)

      Tester Connection Condition Specified Condition
      1C-1 - Auxiliary battery positive terminal Always Below 1 Ω

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  6. CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY (EFI MAIN RELAY) - BODY GROUND) 
    1. Remove the integration relay from the engine room relay block.
    2. Disconnect the integration relay connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      1B-3 - Body ground Always Below 1 Ω

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK → See step   7 

  7. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE 
  8. INSPECT INTEGRATION RELAY (IG2 RELAY) 
    1. Inspect the integration relay. Refer to INSPECTION .

    NG → See step   15 

    OK: Go to next step 

  9. CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY (IG2 RELAY) - ECM) 
    1. Disconnect the ECM connector.
    2. Remove the integration relay from the engine room relay block.
    3. Disconnect the integration relay connector.
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)

      Tester Connection Condition Specified Condition
      1A-4 - A57-28 (IGSW) Always Below 1 Ω

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  10. CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY (IG2 RELAY) - AUXILIARY BATTERY) 
    1. Remove the integration relay from the engine room relay block.
    2. Disconnect the integration relay connector.
    3. Disconnect the negative auxiliary battery terminal.
    4. Disconnect the positive auxiliary battery terminal.
    5. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)

      Tester Connection Condition Specified Condition
      1C-1 - Auxiliary battery positive terminal Always Below 1 Ω

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  11. CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY (IG2 RELAY) - BODY GROUND) 
    1. Remove the integration relay from the engine room relay block.
    2. Disconnect the integration relay connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      1A-3 - Body ground Always Below 1 Ω

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  12. CHECK HARNESS AND CONNECTOR (POWER MANAGEMENT CONTROL ECU - INTEGRATION RELAY (IG2 RELAY)) 
    1. Remove the integration relay from the engine room relay block.
    2. Disconnect the integration relay connector.
    3. Disconnect the power management control ECU connector.
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)

      Tester Connection Condition Specified Condition
      A22-2 (IG2D) - 1A-2 Always Below 1 Ω

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK → See step   13 

  13. CHECK SMART KEY SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING 
  14. REPLACE INTEGRATION RELAY. Refer to  REMOVAL 
  15. REPLACE INTEGRATION RELAY. Refer to  REMOVAL 
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