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Home >> Lexus >> 2023 >> LS 500h >> Repair and Diagnosis >> Hybrid/Electric Powertrain >> Testing and Diagnosis >> Hybrid Control System (W/O Advanced Park) - Diagnostic Codes (10 Of 10) & Circuit Tests (1 Of 2) >> HYBRID CONTROL SYSTEM (w/o Advanced Park) >> ECU Power Source Circuit [10/2017 - 09/2019] >> Procedure

ECU Power Source Circuit [10/2017 - 09/2019]: Procedure

  1. CHECK HYBRID VEHICLE CONTROL ECU ASSEMBLY (+B1, +B2 VOLTAGE) 
    1. Turn the power switch on (IG).
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      G92-4 (+B1) - Body ground Power switch on (IG) 11 to 14 V
      G93-3 (+B2) - Body ground Power switch on (IG) 11 to 14 V
      GTY782023Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Hybrid Vehicle Control ECU Assembly)
    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 ASSEMBLY - BODY GROUND) 
    1. Disconnect the A76, G92 and G93 hybrid vehicle control ECU assembly connectors.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      G92-6 (E1) - Body ground Power switch off Below 1 Ω
      G93-6 (E12) - Body ground Power switch off Below 1 Ω
      A76-2 (E01) - Body ground Power switch off Below 1 Ω
      G92-2 (E02) - Body ground Power switch off Below 1 Ω
      GTY810166Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Rear view of wire harness connector
      (to Hybrid Vehicle Control ECU Assembly)
    3. Reconnect the A76, G92 and G93 hybrid vehicle control ECU assembly connectors.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    GO TO PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [10/2017 - 10/2023] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  3. CHECK HYBRID VEHICLE CONTROL ECU ASSEMBLY (MREL VOLTAGE) 
    1. Turn the power switch on (IG).
    2. Measure the voltage according to the value(s) in the table below.
      GTY828784Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Hybrid Vehicle Control ECU Assembly)

      Standard Voltage

      Tester Connection Condition Specified Condition
      A77-1 (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 ASSEMBLY. Refer to  REMOVAL [10/2017 - 09/2018]  , or refer to  REMOVAL [09/2018 - 10/2020] 

    Result: 

    OK 

    See step  4

  4. CHECK FUSE (PM-IGCT) 
    1. Remove the PM-IGCT fuse from the No. 2 luggage room relay block.
      GTY780085Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 2 Luggage Room 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 terminals Always Below 1 Ω
    3. Install the PM-IGCT fuse.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  11

    Result: 

    OK 

    See step  5

  5. CHECK FUSE (IGCT NO. 1) 
    1. Remove the IGCT NO. 1 fuse from the No. 2 luggage room relay block.
      GTY822904Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 2 Luggage Room Relay Block
      *2 IGCT NO. 1 Fuse
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      IGCT NO. 1 fuse terminals Always Below 1 Ω
    3. Install the IGCT NO. 1 fuse.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  12

    Result: 

    OK 

    See step  6

  6. INSPECT RELAY (IGCT NO. 1) 
    1. Remove the IGCT NO. 1 relay from the No. 2 luggage room relay block.
      GTY776682Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 2 Luggage Room Relay Block
      *2 IGCT NO. 1 Relay
    2. Measure the resistance according to the value(s) in the table below.
      GTY434306Courtesy 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
    3. Install the IGCT NO. 1 relay.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE RELAY (IGCT NO. 1) 

    Result: 

    OK 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU ASSEMBLY - NO. 2 LUGGAGE ROOM RELAY BLOCK) 
    1. Disconnect the G92 and G93 hybrid vehicle control ECU assembly connectors.
    2. Remove the PM-IGCT fuse from the No. 2 luggage room relay block.
      GTY780085Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 2 Luggage Room Relay Block
      *2 PM-IGCT Fuse
    3. Measure the resistance according to the value(s) in the table below.
      GTY780593Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 2 Luggage Room Relay Block *2 PM-IGCT Fuse
      *a Rear view of wire harness connector
      (to Hybrid Vehicle Control ECU Assembly)      		 - -

      Standard Resistance

      Tester Connection Condition Specified Condition
      G92-4 (+B1) - 2 (PM-IGCT fuse) Power switch off Below 1 Ω
      G93-3 (+B2) - 2 (PM-IGCT fuse) Power switch off Below 1 Ω
    4. Reconnect the G92 and G93 hybrid vehicle control ECU assembly 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. 2 LUGGAGE ROOM RELAY BLOCK) 
    1. Remove the IGCT NO. 1 fuse, PM-IGCT fuse and IGCT NO. 1 relay from the No. 2 luggage room relay block.
      GTY825626Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 2 Luggage Room Relay Block
      *2 PM-IGCT Fuse
      *3 IGCT NO. 1 Fuse
      *4 IGCT NO. 1 Relay
    2. Measure the resistance according to the value(s) in the table below.
      GTY818325Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 2 Luggage Room Relay Block
      *2 PM-IGCT Fuse
      *3 IGCT NO. 1 Fuse
      *4 IGCT NO. 1 Relay

      Standard Resistance

      Tester Connection Condition Specified Condition
      3 (IGCT NO. 1 relay) - 2 (IGCT NO. 1 fuse) Power switch off Below 1 Ω
      5 (IGCT NO. 1 relay) - 1 (PM-IGCT fuse) Power switch off Below 1 Ω
    3. Install the IGCT NO. 1 fuse, PM-IGCT fuse and IGCT NO. 1 relay.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  9

  9. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU ASSEMBLY - NO. 2 LUGGAGE ROOM RELAY BLOCK) 
    1. Disconnect the A77 hybrid vehicle control ECU assembly connector.
    2. Remove the IGCT NO. 1 relay from the No. 2 luggage room relay block.
      GTY776682Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 2 Luggage Room Relay Block
      *2 IGCT NO. 1 Relay
    3. Measure the resistance according to the value(s) in the table below.
      GTY787701Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 2 Luggage Room Relay Block *2 IGCT NO. 1 Relay
      *a Rear view of wire harness connector
      (to Hybrid Vehicle Control ECU Assembly)      		 - -

      Standard Resistance

      Tester Connection Condition Specified Condition
      A77-1 (MREL) - 1 (IGCT NO. 1 relay) Power switch off Below 1 Ω
      A77-1 (MREL) or 1 (IGCT NO. 1 relay) - Body ground and other terminals Power switch off 10 kΩ or higher
    4. Install the IGCT NO. 1 relay.
    5. Reconnect the A77 hybrid vehicle control ECU 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 (NO. 2 LUGGAGE ROOM RELAY BLOCK - BODY GROUND) 
    1. Remove the IGCT NO. 1 relay from the No. 2 luggage room relay block.
      GTY776682Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 2 Luggage Room Relay Block
      *2 IGCT NO. 1 Relay
    2. Measure the resistance according to the value(s) in the table below.
      GTY813900Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 2 Luggage Room Relay Block
      *2 IGCT NO. 1 Relay

      Standard Resistance

      Tester Connection Condition Specified Condition
      2 (IGCT NO. 1 relay) - Body ground Power switch off Below 1 Ω
    3. Install the IGCT NO. 1 relay.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    CHECK FOR INTERMITTENT PROBLEMS. Refer to  CHECK FOR INTERMITTENT PROBLEMS [10/2017 - 10/2023] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  11. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU ASSEMBLY - NO. 2 LUGGAGE ROOM RELAY BLOCK) 
    1. Remove the PM-IGCT fuse from the No. 2 luggage room relay block.
      GTY780085Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 2 Luggage Room Relay Block
      *2 PM-IGCT Fuse
    2. Disconnect the G92 and G93 hybrid vehicle control ECU assembly connectors.
    3. Measure the resistance according to the value(s) in the table below.
      GTY828478Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 2 Luggage Room Relay Block *2 PM-IGCT Fuse
      *a Rear view of wire harness connector
      (to Hybrid Vehicle Control ECU Assembly)      		 - -

      Standard Resistance

      Tester Connection Condition Specified Condition
      G92-4 (+B1) or 2 (PM-IGCT fuse) - Body ground and other terminals Power switch off 10 kΩ or higher
      G93-3 (+B2) or 2 (PM-IGCT fuse) - Body ground and other terminals Power switch off 10 kΩ or higher
    4. Reconnect the G92 and G93 hybrid vehicle control ECU assembly connectors.
    5. Install the PM-IGCT fuse.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE FUSE (PM-IGCT) 

    Result: 

    NG 

    See step  13

  12. CHECK HARNESS AND CONNECTOR (NO. 2 LUGGAGE ROOM RELAY BLOCK) 
    1. Disconnect the IGCT NO. 1 fuse, PM-IGCT fuse and IGCT NO. 1 relay from the No. 2 luggage room relay block.
      GTY825626Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 2 Luggage Room Relay Block
      *2 PM-IGCT Fuse
      *3 IGCT NO. 1 Fuse
      *4 IGCT NO. 1 Relay
    2. Measure the resistance according to the value(s) in the table below.
      GTY818325Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 2 Luggage Room Relay Block
      *2 PM-IGCT Fuse
      *3 IGCT NO. 1 Fuse
      *4 IGCT NO. 1 Relay
      STANDARD RESISTANCE:

      Tester Connection Condition Specified Condition
      3 (IGCT NO. 1 relay) or 2 (IGCT NO. 1 fuse) - Body ground and other terminals Power switch off 10 kΩ or higher
      5 (IGCT NO. 1 relay) or 1 (PM-IGCT fuse) - Body ground and other terminals Power switch off 10 kΩ or higher
    3. Install the IGCT NO. 1 fuse, PM-IGCT fuse and IGCT NO. 1 relay.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE FUSE (IGCT NO. 1) 

    Result: 

    NG 

    See step  14

  13. REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result

    Proceed to
    NEXT

    Result: 

    NEXT 

    REPLACE FUSE (PM-IGCT) 

  14. REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result

    Proceed to
    NEXT

    Result: 

    NEXT 

    REPLACE FUSE (IGCT NO. 1) 

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