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Home >> Lexus >> 2012 >> HS 250h >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System (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 (HYBRID VEHICLE CONTROL ECU - BODY GROUND) 
    1. Disconnect the hybrid vehicle control ECU connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      C28-14 (E1) - Body ground Always Below 1 Ω
    3. Reconnect the hybrid vehicle control ECU connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  2. INSPECT HYBRID VEHICLE CONTROL ECU (IGSW VOLTAGE) 
    1. Disconnect the hybrid vehicle control ECU connector.
      Fig 1: Identifying A58 Hybrid Vehicle Control ECU (IGSW Voltage)
      GTY280977Courtesy 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
      A58-57 (IGSW) - Body ground Power switch on (IG) 11 to 14 V
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Hybrid Vehicle Control ECU)
    4. Reconnect the hybrid vehicle control ECU connector.

    NG → See step   7 

    OK: Go to next step 

  3. INSPECT RELAY (IGCT RELAY) 
    1. Remove the IGCT relay from the engine room relay block.
      Fig 2: Inspecting Fan Relay
      GTY139637Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      3 - 5 No auxiliary battery voltage applied across terminals 1 and 2 10 kΩ or higher
      Auxiliary battery voltage applied across terminals 1 and 2 Below 1 Ω
    3. Reinstall the IGCT relay.

    NG → REPLACE RELAY (IGCT RELAY) 

    OK: Go to next step 

  4. CHECK HARNESS AND CONNECTOR (IGCT RELAY - HYBRID VEHICLE CONTROL ECU) 
    1. Remove the IGCT relay from the engine room relay block.
    2. Disconnect the hybrid vehicle control ECU connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)

      Tester Connection Condition Specified Condition
      IGCT relay terminal 5 - A58-1 (+B2) Always Below 1 Ω
      IGCT relay terminal 5 - A58-2 (+B1) Always Below 1 Ω
      IGCT relay terminal 1 - A58-93 (MREL) Always Below 1 Ω
    4. Reconnect the hybrid vehicle control ECU connector.
    5. Reinstall the IGCT relay.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

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

      Standard Resistance (Check for Open)

      Tester Connection Condition Specified Condition
      IGCT relay terminal 3 - Auxiliary battery positive terminal Always Below 1 Ω
    5. Reinstall the IGCT relay.
    6. Reconnect the positive auxiliary battery terminal.
    7. Reconnect the negative auxiliary battery terminal.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  6. CHECK HARNESS AND CONNECTOR (IGCT RELAY - BODY GROUND) 
    1. Remove the IGCT relay from the engine room relay block.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)

      Tester Connection Condition Specified Condition
      IGCT relay terminal 2 - Body ground Always Below 1 Ω
    3. Reinstall the IGCT relay.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK → See step   13 

  7. INSPECT NO. 1 INTEGRATION RELAY (IG2 RELAY) 
    1. Inspect the No. 1 integration relay. Refer to INSPECTION .

    NG → See step   12 

    OK: Go to next step 

  8. CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY (IG2 RELAY) - HYBRID VEHICLE CONTROL ECU) 
    1. Disconnect the hybrid vehicle control ECU connector.
    2. Remove the No. 1 integration relay from the engine room relay block.
    3. Disconnect the No. 1 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 - A58-57 (IGSW) Always Below 1 Ω
    5. Reconnect the hybrid vehicle control ECU connector.
    6. Reconnect the No. 1 integration relay connector.
    7. Reinstall the No. 1 integration relay.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  9. CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY (IG2 RELAY) - AUXILIARY BATTERY) 
    1. Remove the No. 1 integration relay from the engine room relay block.
    2. Disconnect the No. 1 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
    6. Reconnect the No. 1 integration relay connector.
    7. Reinstall the No. 1 integration relay.
    8. Reconnect the positive auxiliary battery terminal.
    9. Reconnect the negative auxiliary battery terminal.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  10. CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY (IG2 RELAY) - BODY GROUND) 
    1. Remove the No. 1 integration relay from the engine room relay block.
    2. Disconnect the No. 1 integration relay connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)

      Tester Connection Condition Specified Condition
      1A-3 - Body ground Always Below 1 Ω
    4. Reconnect the No. 1 integration relay connector.
    5. Reinstall the No. 1 integration relay.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  11. CHECK HARNESS AND CONNECTOR (POWER MANAGEMENT CONTROL ECU - NO. 1 INTEGRATION RELAY (IG2 RELAY)) 
    1. Remove the No. 1 integration relay from the engine room relay block.
    2. Disconnect the No. 1 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
      F51-8 (IG2D) - 1A-2 Always Below 1 Ω
    5. Reconnect the No. 1 integration relay connector.
    6. Reinstall the No. 1 integration relay.
    7. Reconnect the power management control ECU connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK → See step   14 

  12. REPLACE NO. 1 INTEGRATION RELAY. Refer to  REMOVAL 
  13. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE 
  14. CHECK SMART ACCESS SYSTEM WITH PUSH-BUTTON START. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING 
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