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ECU Power Source Circuit [10/2022 - ]: Procedure

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  1. CHECK HYBRID VEHICLE CONTROL ECU ASSEMBLY (+B1, +B2 VOLTAGE) 
    1. Measure the voltage according to the value(s) in the table below.
      GTY1132789Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Hybrid Vehicle Control ECU)      		 - -

      Standard Voltage

      Tester Connection Condition Specified Condition
      C59-8 (+B1) - Body ground Ignition switch ON 11 to 14 V
      A21-10 (+B2) - Body ground Ignition switch ON 11 to 14 V

      Result

      Proceed to
      OK
      NG
    2. Turn the ignition switch off.

    Result: 

    NG 

    See step  3

    Result: 

    OK 

    See step  2

  2. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - BODY GROUND) 
    1. Disconnect the hybrid vehicle control ECU connectors.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      C59-1 (E1) - Body ground Always Below 1 Ω
      A21-12 (E01) - Body ground Always Below 1 Ω
      A21-24 (E12) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG
    3. Reconnect the hybrid vehicle control ECU connectors.

    Result: 

    OK 

    GO TO PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [10/2022 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  3. CHECK HYBRID VEHICLE CONTROL ECU ASSEMBLY (MREL VOLTAGE) 
    1. Measure the voltage according to the value(s) in the table below.
      GTY1131875Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Hybrid Vehicle Control ECU)      		 - -

      Standard Voltage

      Tester Connection Condition Specified Condition
      C59-10 (MREL) - Body ground Ignition switch ON 11 to 14 V

      Result

      Proceed to
      OK
      NG
    2. Turn the Ignition switch off.

    Result: 

    NG 

    REPLACE HYBRID VEHICLE CONTROL ECU ASSEMBLY. Refer to  REMOVAL [10/2022 - ] 

    Result: 

    OK 

    See step  4

  4. CHECK FUSE (PM-IGCT) 
    1. Remove the PM-IGCT fuse from the No. 2 engine room relay block and No. 2 junction block assembly.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      PM-IGCT fuse terminals Always Below 1 Ω

      Result

      Proceed to
      OK
      NG
    3. Install the PM-IGCT fuse.

    Result: 

    NG 

    See step  10

    Result: 

    OK 

    See step  5

  5. INSPECT RELAY (IGCT NO. 1) 
    1. Remove the IGCT NO. 1 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.
      GTY1104539Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 IGCT NO. 1 Relay

      Standard Resistance

      Tester Connection Condition Specified Condition
      3 - 5 Auxiliary battery voltage not applied between terminals 1 and 2 10 kΩ or higher
      Auxiliary battery voltage applied between terminals 1 and 2 Below 1 Ω

      Result

      Proceed to
      OK
      NG
    3. Install the IGCT No. 1 relay.

    Result: 

    NG 

    REPLACE RELAY (IGCT NO. 1) 

    Result: 

    OK 

    See step  6

  6. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - NO. 1 ENGINE ROOM RELAY BLOCK AND NO. 1 JUNCTION BLOCK ASSEMBLY) 
    1. Disconnect the hybrid vehicle control ECU connectors.
    2. Remove the PM-IGCT fuse from the No. 2 engine room relay block and No. 2 junction block assembly.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      C59-8 (+B1) - 2 (PM-IGCT fuse holder) Always Below 1 Ω
      A21-10 (+B2) - 2 (PM IGCT fuse holder) Always Below 1 Ω

      Result

      Proceed to
      OK
      NG
    4. Reconnect the hybrid vehicle control ECU connectors.
    5. Install the PM-IGCT fuse.

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (IGCT NO. 1 RELAY - PM-IGCT FUSE) 
    1. Remove the IGCT NO. 1 relay from the No. 1 engine room relay block and No. 1 junction block assembly.
    2. Remove the PM-IGCT fuse from the No. 2 engine room relay block and No. 2 junction block assembly.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      5 (IGCT NO. 1 relay holder) - 1 (PM-IGCT fuse terminal) Always Below 1 Ω
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      3 (IGCT NO. 1 relay holder) - Body ground Always 7.5 to 14 V

      Result

      Proceed to
      OK
      NG
    5. Install the PM IGCT fuse and IGCT NO. 1 relay.

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  8

  8. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - NO. 1 ENGINE ROOM RELAY BLOCK AND NO. 1 JUNCTION BLOCK ASSEMBLY) 
    1. Disconnect the hybrid vehicle control ECU connector.
    2. Remove the IGCT NO. 1 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
      C59-10 (MREL) - 1 (IGCT NO. 1 relay holder) Always Below 1 Ω
      C59-10 (MREL) or 1 (IGCT NO. 1 relay holder) - Body ground and other terminals Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG
    4. Install the IGCT NO. 1 relay.
    5. Reconnect the hybrid vehicle control ECU connector.

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  9

  9. CHECK HARNESS AND CONNECTOR (NO. 1 ENGINE ROOM RELAY BLOCK AND NO. 1 JUNCTION BLOCK ASSEMBLY - BODY GROUND) 
    1. Remove the IGCT NO. 1 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 (IGCT NO. 1 relay holder) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG
    3. Install the IGCT NO. 1 relay.

    Result: 

    OK 

    CHECK FOR INTERMITTENT PROBLEMS. Refer to  CHECK FOR INTERMITTENT PROBLEMS [10/2022 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  10. CHECK HARNESS AND CONNECTOR (NO. 2 ENGINE ROOM RELAY BLOCK AND NO. 2 JUNCTION BLOCK ASSEMBLY - HYBRID VEHICLE CONTROL ECU) 
    1. Remove the PM-IGCT fuse from the No. 2 engine room relay block and No. 2 junction block assembly.
    2. Disconnect the hybrid vehicle control ECU connectors.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      C59-8 (+B1) or 2 (PM-IGCT fuse holder) - Body ground and other terminals Always 10 kΩ or higher
      A21-10 (+B2) or 2 (PM-IGCT fuse holder) - Body ground and other terminals Always 10 kΩ or higher
    4. Reconnect the hybrid vehicle control ECU connectors.
    5. Install the PM-IGCT fuse.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE FUSE (PM IGCT) 

    Result: 

    NG 

    See step  11

  11. REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result

    Proceed to
    NEXT

    Result: 

    NEXT 

    REPLACE FUSE (PM IGCT) 

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