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Home >> Toyota >> 2020 >> Avalon Limited >> Repair and Diagnosis >> External Pages >> Different car >> Section 32 (Hybrid Control System - Diagnostic Codes (U0111-U0424) & Circuit Tests (Lithium-Ion)) >> HYBRID CONTROL SYSTEM (for LITHIUM-ION BATTERY) >> ECU Power Source Circuit [08/2020 - ] >> Procedure

ECU Power Source Circuit [08/2020 - ]: Procedure

WARNING: This page is about a different car, the 2022 Toyota Avalon and 2021 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK HYBRID VEHICLE CONTROL ECU (+B1, +B2 VOLTAGE) 
    1. Turn the power switch on (IG).
    2. Measure the voltage according to the value(s) in the table below.
      GTY907628Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Hybrid Vehicle Control ECU)

      Standard Voltage

      Tester Connection Condition Specified Condition
      A24-4 (+B1) - Body ground Power switch on (IG) 11 to 14 V
      A23-1 (+B2) - Body ground Power switch on (IG) 11 to 14 V
    3. Turn the power switch off.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  3

    Result: 

    OK 

    See step  2

  2. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - BODY GROUND) 
    1. Disconnect the G46 and G47 hybrid vehicle control ECU connectors.
    2. Measure the resistance according to the value(s) in the table below.
      GTY885239Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Rear view of wire harness connector
      (to Hybrid Vehicle Control ECU)

      Standard Resistance

      Tester Connection Condition Specified Condition
      G46-6 (E1) - Body ground Always Below 1 Ω
      G46-5 (E01) - Body ground Always Below 1 Ω
      G47-5 (E02) - Body ground Always Below 1 Ω
      G47-4 (E12) - Body ground Always Below 1 Ω
    3. Reconnect the G46 and G47 hybrid vehicle control ECU connectors.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    GO TO PROBLEM SYMPTOMS TABLE. Refer to  CHECK FOR INTERMITTENT PROBLEMS [08/2020 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  3. CHECK HYBRID VEHICLE CONTROL ECU (MREL VOLTAGE) 
    1. Turn the power switch on (IG).
    2. Measure the voltage according to the value(s) in the table below.
      GTY907629Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Hybrid Vehicle Control ECU)

      Standard Voltage

      Tester Connection Condition Specified Condition
      A24-6 (MREL) - Body ground Power switch on (IG) 11 to 14 V
    3. Turn the power switch off.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE HYBRID VEHICLE CONTROL ECU. Refer to  REMOVAL [04/2018 - 08/2021]  , or refer to  REMOVAL [08/2021 - ] 

    Result: 

    OK 

    See step  4

  4. CHECK FUSE (PM-IGCT) 
    1. Remove the PM-IGCT fuse from the No. 4 relay block.
      GTY772297Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 4 Relay Block
      *2 PM-IGCT Fuse
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      PM-IGCT fuse Always Below 1 Ω
    3. Install the PM-IGCT fuse.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  12

    Result: 

    OK 

    See step  5

  5. CHECK FUSIBLE LINK BLOCK ASSEMBLY (IGCT FUSE) 
    1. Disconnect the cable from the negative (-) auxiliary battery terminal.
    2. Disconnect the cable from the positive (+) auxiliary battery terminal.
    3. Disconnect the 7B fusible link block assembly connector.
      GTY908300Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      7B-1 - A-1 (Positive (+) auxiliary battery terminal) Power switch off Below 1 Ω
      GTY905509Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Fusible Link Block Assembly
      *a Component without harness connected
      (Fusible Link Block Assembly)
    5. Reconnect the 7B fusible link block assembly connector.
    6. Reconnect the cable to the positive (+) auxiliary battery terminal.
    7. Reconnect the cable to the negative (-) auxiliary battery terminal.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  13

    Result: 

    OK 

    See step  6

  6. INSPECT RELAY (IGCT) 
    1. Remove the IGCT relay from the No. 3 relay block.
      GTY747315Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 3 Relay Block
      *2 IGCT Relay
    2. Measure the resistance according to the value(s) in the table below.
      GTY434306Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 IGCT 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
    3. Install the IGCT relay.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE RELAY (IGCT) 

    Result: 

    OK 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (NO. 4 RELAY BLOCK - HYBRID VEHICLE CONTROL ECU) 
    1. Disconnect the A23 and A24 hybrid vehicle control ECU connectors.
    2. Remove the PM-IGCT fuse from the No. 4 relay block.
    3. Measure the resistance according to the value(s) in the table below.
      GTY939378Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 4 Relay Block *2 PM-IGCT Fuse Holder
      *a Rear view of wire harness connector
      (to Hybrid Vehicle Control ECU)      		 - -

      Standard Resistance

      Tester Connection Condition Specified Condition
      A24-4 (+B1) - 2 (PM-IGCT fuse holder) Always Below 1 Ω
      A23-1 (+B2) - 2 (PM-IGCT fuse holder) Always Below 1 Ω
    4. Reconnect the A23 and A24 hybrid vehicle control ECU connectors.
    5. Install the PM-IGCT fuse.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  8

  8. CHECK HARNESS AND CONNECTOR (NO. 3 RELAY BLOCK - NO. 4 RELAY BLOCK) 
    1. Remove the IGCT relay from the No. 3 relay block.
    2. Remove the PM-IGCT fuse from the No. 4 relay block.
    3. Measure the resistance according to the value(s) in the table below.
      GTY904079Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 3 Relay Block *2 No. 4 Relay Block
      *3 IGCT Relay Holder *4 PM-IGCT Fuse Holder

      Standard Resistance

      Tester Connection Condition Specified Condition
      5 (IGCT relay holder) - 1 (PM-IGCT fuse holder) Always Below 1 Ω
    4. Install the PM-IGCT fuse.
    5. Install the IGCT relay.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  9

  9. CHECK HARNESS AND CONNECTOR (FUSIBLE LINK BLOCK ASSEMBLY - NO. 3 RELAY BLOCK) 
    1. Disconnect the 7B fusible link block assembly connector.
    2. Remove the IGCT relay from the No. 3 relay block.
      GTY911764Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 3 Relay Block
      *2 IGCT Relay Holder
      *a Front view of wire harness connector
      (to Fusible Link Block Assembly)
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      3 (IGCT relay holder) - 7B-1 Always Below 1 Ω
    4. Install the IGCT relay.
    5. Reconnect the 7B fusible link block assembly connector.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  10

  10. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - NO. 3 RELAY BLOCK) 
    1. Disconnect the A24 hybrid vehicle control ECU connector.
    2. Remove the IGCT relay from the No. 3 relay block.
    3. Measure the resistance according to the value(s) in the table below.
      GTY915689Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 3 Relay Block *2 IGCT Relay Holder
      *a Rear view of wire harness connector
      (to Hybrid Vehicle Control ECU)      		 - -

      Standard Resistance

      Tester Connection Condition Specified Condition
      A24-6 (MREL) - 1 (IGCT relay holder) Always Below 1 Ω
      A24-6 (MREL) or 1 (IGCT relay holder) - Body ground and other terminals Always 10 kΩ or higher
    4. Install the IGCT relay.
    5. Reconnect the A24 hybrid vehicle control ECU connector.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  11

  11. CHECK HARNESS AND CONNECTOR (NO. 3 RELAY BLOCK - BODY GROUND) 
    1. Remove the IGCT relay from the No. 3 relay block.
    2. Measure the resistance according to the value(s) in the table below.
      GTY888446Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 3 Relay Block
      *2 IGCT Relay Holder

      Standard Resistance

      Tester Connection Condition Specified Condition
      2 (IGCT relay holder) - Body ground Always Below 1 Ω
    3. Install the IGCT relay.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    CHECK FOR INTERMITTENT PROBLEMS. Refer to  CHECK FOR INTERMITTENT PROBLEMS [08/2020 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  12. CHECK HARNESS AND CONNECTOR (NO. 4 RELAY BLOCK - HYBRID VEHICLE CONTROL ECU) 
    1. Remove the PM-IGCT fuse from the No. 4 relay block.
    2. Disconnect the A23 and A24 hybrid vehicle control ECU connectors.
    3. Measure the resistance according to the value(s) in the table below.
      GTY939378Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 4 Relay Block *2 PM-IGCT Fuse Holder
      *a Rear view of wire harness connector
      (to Hybrid Vehicle Control ECU)      		 - -

      Standard Resistance

      Tester Connection Condition Specified Condition
      A24-4 (+B1) or 2 (PM-IGCT fuse holder) - Body ground and other terminals Always 10 kΩ or higher
      A23-1 (+B2) or 2 (PM-IGCT fuse holder) - Body ground and other terminals Always 10 kΩ or higher
    4. Reconnect the A23 and A24 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  15

  13. CHECK HARNESS AND CONNECTOR (FUSIBLE LINK BLOCK ASSEMBLY - NO. 3 RELAY BLOCK) 
    1. Disconnect the 7B fusible link block assembly connector.
    2. Remove the IGCT relay from the No. 3 relay block.
    3. Measure the resistance according to the value(s) in the table below.
      GTY911764Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 3 Relay Block
      *2 IGCT Relay Holder
      *a Front view of wire harness connector
      (to Fusible Link Block Assembly)
      STANDARD RESISTANCE:

      Tester Connection Condition Specified Condition
      3 (IGCT relay holder) or 7B-1 - Body ground and other terminals Always 10 kΩ or higher
    4. Install the IGCT relay.
    5. Reconnect the 7B fusible link block assembly connector.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  16

    Result: 

    OK 

    See step  14

  14. CHECK HARNESS AND CONNECTOR (NO. 3 RELAY BLOCK - NO. 4 RELAY BLOCK) 
    1. Remove the IGCT relay from the No. 3 relay block.
    2. Remove the PM-IGCT fuse from the No. 4 relay block.
    3. Measure the resistance according to the value(s) in the table below.
      GTY904079Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 3 Relay Block *2 No. 4 Relay Block
      *3 IGCT Relay Holder *4 PM-IGCT Fuse Holder

      Standard Resistance

      Tester Connection Condition Specified Condition
      5 (IGCT relay holder) or 1 (PM-IGCT fuse holder) - Body ground and other terminals Always 10 kΩ or higher
    4. Install the PM-IGCT fuse.
    5. Install the IGCT relay.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE FUSIBLE LINK BLOCK ASSEMBLY (IGCT FUSE) 

    Result: 

    NG 

    See step  17

  15. REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result

    Proceed to
    NEXT

    Result: 

    NEXT 

    REPLACE FUSE (PM-IGCT) 

  16. REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result

    Proceed to
    NEXT

    Result: 

    NEXT 

    REPLACE FUSIBLE LINK BLOCK ASSEMBLY (IGCT FUSE) 

  17. REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result

    Proceed to
    NEXT

    Result: 

    NEXT 

    REPLACE FUSIBLE LINK BLOCK ASSEMBLY (IGCT FUSE) 

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