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Home >> Lexus >> 2021 >> LS 500h RWD >> Repair and Diagnosis >> Restraints >> Air Bag, SRS >> Airbag System (W/O Advanced Park) - Diagnostic Codes (3 Of 3) >> AIRBAG SYSTEM (w/o Advanced Park) >> SRS Warning Light Remains ON [10/2020 - 10/2023] >> Procedure

SRS Warning Light Remains ON [10/2020 - 10/2023]: Procedure

  1. CHECK SRS WARNING LIGHT OPERATION 
    1. Turn the power switch on (IG) and check the SRS warning light condition.

      HINT: 

      The primary check is performed for approximately 6 seconds after the power switch is turned on (IG).

      Result

      Result Proceed to
      After the primary check period, the SRS warning light remains on. A
      After the primary check period, the SRS warning light goes off and comes on again. B

    Result: 

    B 

    See step  6

    Result: 

    A 

    See step  2

  2. CHECK AUXILIARY BATTERY 
    1. Measure the auxiliary battery voltage with the power switch off.

      Standard voltage

      11 to 14 V

      HINT: 

      It may be possible to tell whether the auxiliary battery is discharged by operating the horn.

      If the voltage is below 11 V, recharge or replace the auxiliary battery before proceeding to the next step.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE OR RECHARGE AUXILIARY BATTERY 

    Result: 

    OK 

    See step  3

  3. CHECK CONNECTOR 
    1. Turn the power switch off.
    2. Disconnect the cable from the negative (-) auxiliary battery terminal, and wait for at least 60 seconds.
    3. Check that the connector is properly connected to the airbag ECU assembly.

      OK

      The connector is properly connected.

      HINT: 

      If the connector is not properly connected, reconnect the connector and proceed to the next inspection.

    4. Disconnect the connector from the airbag ECU assembly.
    5. Check that the terminals of the connector are not deformed or damaged.

      OK

      The terminals are not deformed or damaged.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE INSTRUMENT PANEL WIRE 

    Result: 

    OK 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (AIRBAG ECU ASSEMBLY - AUXILIARY BATTERY AND BODY GROUND) 
    1. Connect the cable to the negative (-) auxiliary battery terminal.
    2. Turn the power switch on (IG).
    3. Operate all components of the electrical systems (defogger, wipers, headlights, heater blower, etc.).
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      G11-36 (IG2) - Body ground Power switch on (IG) 8 to 16 V
    5. Turn the power switch off.
    6. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      G11-33 (E1) - Body ground Always Below 1 Ω
      G11-32 (E2) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE INSTRUMENT PANEL WIRE 

    Result: 

    OK 

    See step  5

  5. CHECK SRS WARNING LIGHT (SHORT TO GROUND) 
    1. Turn the power switch on (IG) and check the SRS warning light condition.

      OK

      After the primary check period, the SRS warning light turns off for approximately 10 seconds and then turns back on.

      HINT: 

      The primary check period is approximately 6 seconds after the power switch is turned on (IG).

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE AIRBAG ECU ASSEMBLY. Refer to  REMOVAL [10/2020 - 11/2021]  , or refer to  REMOVAL [11/2021 - 10/2022]  , or refer to  REMOVAL [10/2022 - 10/2023] 

    Result: 

    NG 

    REPLACE COMBINATION METER ASSEMBLY. Refer to  REMOVAL [10/2020 - 11/2021]  , or refer to  REMOVAL [11/2021 - 10/2023] 

  6. CHECK CAN COMMUNICATION SYSTEM 
    1. Check if a CAN communication DTC is output.

      Refer to HOW TO PROCEED WITH TROUBLESHOOTING [10/2020 - 11/2021] , or refer to HOW TO PROCEED WITH TROUBLESHOOTING [11/2021 - 10/2023]

      Result

      Proceed to
      DTCs are output
      DTC is not output

    Result: 

    DTCs are output 

    GO TO CAN COMMUNICATION SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [10/2020 - 11/2021]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [11/2021 - 10/2023] 

    Result: 

    DTC is not output 

    See step  7

  7. CHECK AUXILIARY BATTERY 
    1. Measure the auxiliary battery voltage with the power switch off.

      Standard voltage

      11 to 14 V

      HINT: 

      It may be possible to tell whether the auxiliary battery is discharged by operating the horn.

      If the voltage is below 11 V, recharge or replace the auxiliary battery before proceeding to the next step.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE OR RECHARGE AUXILIARY BATTERY 

    Result: 

    OK 

    See step  8

  8. CHECK CONNECTOR 
    1. Turn the power switch off.
    2. Disconnect the cable from the negative (-) auxiliary battery terminal, and wait for at least 60 seconds.
    3. Check that the connector is properly connected to the airbag ECU assembly.

      OK

      The connector is properly connected.

      HINT: 

      If the connector is not properly connected, reconnect the connector and proceed to the next inspection.

    4. Disconnect the connector from the airbag ECU assembly.
    5. Check that the terminals of the connector are not deformed or damaged.

      OK

      The terminals are not deformed or damaged.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE INSTRUMENT PANEL WIRE 

    Result: 

    OK 

    See step  9

  9. CHECK HARNESS AND CONNECTOR (AIRBAG ECU ASSEMBLY - AUXILIARY BATTERY AND BODY GROUND) 
    1. Connect the cable to the negative (-) auxiliary battery terminal.
    2. Turn the power switch on (IG).
    3. Operate all components of the electrical systems (defogger, wipers, headlights, heater blower, etc.).
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      G11-36 (IG2) - Body ground Power switch on (IG) 8 to 16 V
    5. Turn the power switch off.
    6. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      G11-33 (E1) - Body ground Always Below 1 Ω
      G11-32 (E2) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE INSTRUMENT PANEL WIRE 

    Result: 

    OK 

    See step  10

  10. CHECK CONNECTOR 
    1. Disconnect the cable from the negative (-) auxiliary battery terminal, and wait for at least 60 seconds.
    2. Check that the connector is properly connected to the combination meter assembly.

      OK

      The connector is properly connected.

      HINT: 

      If the connector is not properly connected, reconnect the connector and proceed to the next inspection.

    3. Disconnect the connector from the combination meter assembly.
    4. Check that the terminals of the connector are not deformed or damaged.

      OK

      The terminals are not deformed or damaged.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE CONNECTOR 

    Result: 

    OK 

    See step  11

  11. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - AUXILIARY BATTERY AND BODY GROUND) 
    1. Connect the cable to the negative (-) auxiliary battery terminal, and wait for at least 2 seconds.
    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
      G34-21 (IG+) - Body ground Power switch on (IG) 11 to 14 V
      G34-22 (B) - Body ground Power switch off 11 to 14 V
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      G34-31 (ES) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  12

  12. CHECK SRS WARNING LIGHT 
    1. Disconnect the cable from the negative (-) auxiliary battery terminal, and wait for at least 60 seconds.
    2. Connect the connector to the combination meter assembly.
    3. Connect the cable to the negative (-) auxiliary battery terminal.
    4. Turn the power switch on (IG) and check the SRS warning light condition.

      OK

      After the primary check period, the SRS warning light turns off for approximately 10 seconds and then turns back on.

      HINT: 

      The primary check period is approximately 6 seconds after the power switch is turned on (IG).

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE AIRBAG ECU ASSEMBLY. Refer to  REMOVAL [10/2020 - 11/2021]  , or refer to  REMOVAL [11/2021 - 10/2022]  , or refer to  REMOVAL [10/2022 - 10/2023] 

    Result: 

    NG 

    REPLACE COMBINATION METER ASSEMBLY. Refer to  REMOVAL [10/2020 - 11/2021]  , or refer to  REMOVAL [11/2021 - 10/2023] 

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