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ECM Power Source Circuit [01/2019 - 09/2022]: Procedure

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  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
      C77-59 (E1) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  2

  2. CHECK TERMINAL VOLTAGE (IGSW TERMINAL VOLTAGE) 
    GTY850931Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Front view of wire harness connector
    (to ECM)
    1. Disconnect the ECM connector.
    2. Turn the ignition switch to ON.
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A46-6 (IGSW) - Body ground Ignition switch ON 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  7

    Result: 

    OK 

    See step  3

  3. INSPECT EFI-MAIN RELAY 
    1. Inspect the EFI-MAIN relay.

      Refer to PROCEDURE - Step 2

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE EFI-MAIN RELAY 

    Result: 

    OK 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (EFI-MAIN RELAY - BODY GROUND) 
    1. Remove the EFI-MAIN relay from the No. 1 engine room relay block and No. 1 junction block assembly.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      2 (EFI-MAIN relay) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  5

  5. CHECK HARNESS AND CONNECTOR (EFI-MAIN RELAY - ECM) 
    1. Disconnect the ECM connector.
    2. Remove the EFI-MAIN relay from the No. 1 engine room relay block and No. 1 junction block assembly.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      1 (EFI-MAIN relay) - A46-46 (MREL) Always Below 1 Ω
      3 (EFI-MAIN relay) - A46-2 (+B) Always Below 1 Ω
      3 (EFI-MAIN relay) - A46-3 (+B2) Always Below 1 Ω
      1 (EFI-MAIN relay) or A46-46 (MREL) - Body ground and other terminals Always 10 kΩ or higher
      3 (EFI-MAIN relay), A46-2 (+B) or A46-3 (+B2) - Body ground and other terminals Always 10 kΩ or higher

      HINT: 

      If a short is detected in any of the above circuits, there may be a malfunction in the circuit of a connected ECU.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  6

  6. CHECK TERMINAL VOLTAGE (POWER SOURCE OF EFI-MAIN RELAY) 
    GTY906365Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *1 NO. 1 Engine Room Relay Block and NO. 1 Junction Block Assembly
    *2 EFI-MAIN Relay
    1. Remove the EFI-MAIN relay from the No. 1 engine room relay block and No. 1 junction block assembly.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      5 (EFI-MAIN relay) - Body ground Always 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [01/2019 - 09/2022] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - EFI-MAIN RELAY) 

  7. CHECK TERMINAL VOLTAGE (POWER SOURCE OF NO. 1 INTEGRATION RELAY) 
    GTY901804Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Front view of wire harness connector
    (to No. 1 Integration Relay)
    1. Disconnect the No. 1 integration relay connector.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      1A-10 - Body ground Always 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - NO. 1 INTEGRATION RELAY) 

    Result: 

    OK 

    See step  8

  8. INSPECT NO. 1 INTEGRATION RELAY (IG2 NO. 1 RELAY) 
    1. Inspect the No. 1 integration relay (IG2 NO. 1 relay).

      Refer to INSPECTION [01/2019 - 09/2022]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE NO. 1 INTEGRATION RELAY. Refer to  REMOVAL [01/2019 - 03/2019]  , or refer to  REMOVAL [03/2019 - 09/2022] 

    Result: 

    OK 

    See step  9

  9. CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY - ECM) 
    1. Disconnect the No. 1 integration relay connector.
    2. Disconnect the ECM connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      1A-9 - A46-6 (IGSW) Always Below 1 Ω
      1A-9 or A46-6 (IGSW) - Body ground and other terminals Always 10 kΩ or higher

      HINT: 

      If a short is detected in any of the above circuits, there may be a malfunction in the circuit of a connected ECU.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  10

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

      Standard Resistance

      Tester Connection Condition Specified Condition
      1A-8 - Body ground Always Below 1 Ω

      Result

      Result Proceed to
      OK (w/ Smart Key System) A
      OK (w/o Smart Key System) B
      NG C

    Result: 

    B 

    See step  12

    Result: 

    C 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    A 

    See step  11

  11. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - NO. 1 INTEGRATION RELAY) 
    1. Disconnect the certification ECU (smart key ECU assembly) connector.
    2. Disconnect the No. 1 integration relay connector.
    3. Disconnect the instrument panel junction block assembly 4F connector.

      HINT: 

      Disconnect the IG1-NO. 1, IG1-NO. 2 and IG2-NO. 2 relays connected between the checked terminals as the coil inside the relay influences the measurement value.

    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      I1-15 (IG1D) - 1A-7 Always Below 1 Ω
      I1-15 (IG1D) or 1A-7 - Body ground and other terminals Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    GO TO SMART KEY SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [01/2019 - 09/2022] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  12. INSPECT IGNITION OR STARTER SWITCH ASSEMBLY 
    1. Inspect the ignition or starter switch assembly.

      Refer to INSPECTION [01/2019 - 11/2022]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE IGNITION OR STARTER SWITCH ASSEMBLY. Refer to  REMOVAL [01/2019 - 11/2022] 

    Result: 

    OK 

    See step  13

  13. CHECK HARNESS AND CONNECTOR (IGNITION OR STARTER SWITCH ASSEMBLY - NO. 1 INTEGRATION RELAY) 
    1. Disconnect the ignition or starter switch assembly connector.
    2. Disconnect the No. 1 integration relay connector.
    3. Disconnect the instrument panel junction block assembly 4F connector.

      HINT: 

      Disconnect the IG1-NO. 1, IG1-NO. 2 and IG2-NO. 2 relays connected between the checked terminals as the coil inside the relay influences the measurement value.

    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      I12-8 (IG1) - 1A-7 Always Below 1 Ω
      I12-8 (IG1) or 1A-7 - Body ground and other terminals Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - IGNITION OR STARTER SWITCH ASSEMBLY) 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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