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Home >> Lexus >> 2021 >> UX 250h Luxury >> Repair and Diagnosis >> Restraints >> Air Bag, SRS >> Airbag System - Diagnostic Codes (3 Of 3) & Symptom Tests) >> Airbag System >> SRS Warning Light Remains ON [10/2018 - 07/2022] >> Procedure

SRS Warning Light Remains ON [10/2018 - 07/2022]: Procedure

  1. CHECK SRS WARNING LIGHT OPERATION 
    1. Turn the ignition switch to ON and check the SRS warning light condition.

      HINT: 

      The primary check is performed for approximately 6 seconds after the ignition switch is turned to ON.

      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 turns off and comes on again. B

    Result: 

    B 

    See step  6

    Result: 

    A 

    See step  2

  2. CHECK AUXILIARY BATTERY VOLTAGE 
    1. Measure the voltage of the auxiliary battery with the ignition switch off.

      Standard Voltage

      11 to 14 V

      Result

      Result Proceed to
      OK A
      NG (for HV Model) B
      NG (for Gasoline Model) C

    Result: 

    B 

    INSPECT CHARGING SYSTEM AND AUXILIARY BATTERY. Refer to  ON-VEHICLE INSPECTION [10/2018 - ] 

    Result: 

    C 

    INSPECT CHARGING SYSTEM AND AUXILIARY BATTERY. Refer to  ON-VEHICLE INSPECTION [10/2018 - 07/2022] 

    Result: 

    A 

    See step  3

  3. CHECK CONNECTOR 
    1. Turn the ignition switch off.
    2. Disconnect the cable from the negative (-) auxiliary battery terminal.
      WARNING:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) auxiliary battery terminal to disable the SRS system.

    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 WIRE HARNESS 

    Result: 

    OK 

    See step  4

  4. CHECK WIRE HARNESS (AIRBAG ECU ASSEMBLY - BODY GROUND) 
    1. Connect the cable to the negative (-) auxiliary battery terminal.
      GTY809043Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Airbag ECU Assembly)
    2. Turn the ignition switch to ON.
    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
      F57-36 (IG2) - Body ground Ignition switch ON 8 to 16 V
    5. Turn the ignition switch off.
    6. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      F57-33 (E1) - Body ground Always Below 1 Ω
      F57-32 (E2) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE WIRE HARNESS 

    Result: 

    OK 

    See step  5

  5. CHECK SRS WARNING LIGHT 
    1. Turn the ignition switch to ON 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 ignition switch is turned to ON.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE AIRBAG ECU ASSEMBLY. Refer to  REMOVAL [10/2018 - 07/2022] 

    Result: 

    NG 

    REPLACE COMBINATION METER ASSEMBLY. Refer to  REMOVAL [10/2018 - 07/2022] 

  6. CHECK CAN COMMUNICATION SYSTEM 
    1. Using the Techstream, check if the CAN communication system is functioning normally.

      OK

      CAN communication system is functioning normally.

      HINT: 

      Refer to Communication Bus Check in CAN Communication System.

      Result

      Result Proceed to
      OK A
      NG (for HV Model) B
      NG (for Gasoline Model) C

    Result: 

    B 

    GO TO CAN COMMUNICATION SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [10/2018 - ] 

    Result: 

    C 

    GO TO CAN COMMUNICATION SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [10/2018 - 07/2022] 

    Result: 

    A 

    See step  7

  7. CHECK AUXILIARY BATTERY VOLTAGE 
    1. Measure the voltage of the auxiliary battery with the ignition switch off.

      Standard Voltage

      11 to 14 V (IG OFF)

      Result

      Result Proceed to
      OK A
      NG (for HV Model) B
      NG (for Gasoline Model) C

    Result: 

    B 

    INSPECT CHARGING SYSTEM AND AUXILIARY BATTERY. Refer to  ON-VEHICLE INSPECTION [10/2018 - ] 

    Result: 

    C 

    INSPECT CHARGING SYSTEM AND AUXILIARY BATTERY. Refer to  ON-VEHICLE INSPECTION [10/2018 - 07/2022] 

    Result: 

    A 

    See step  8

  8. CHECK CONNECTOR 
    1. Turn the ignition switch off.
    2. Disconnect the cable from the negative (-) auxiliary battery terminal.
      WARNING:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) auxiliary battery terminal to disable the SRS system.

    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 WIRE HARNESS 

    Result: 

    OK 

    See step  9

  9. CHECK WIRE HARNESS (AIRBAG ECU ASSEMBLY - BODY GROUND) 
    1. Connect the cable to the negative (-) auxiliary battery terminal.
      GTY809043Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Airbag ECU Assembly)
    2. Turn the ignition switch to ON.
    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
      F57-36 (IG2) - Body ground Ignition switch ON 8 to 16 V
    5. Turn the ignition switch off.
    6. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      F57-33 (E1) - Body ground Always Below 1 Ω
      F57-32 (E2) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE WIRE HARNESS 

    Result: 

    OK 

    See step  10

  10. CHECK CONNECTOR 
    1. Disconnect the cable from the negative (-) auxiliary battery terminal.
      WARNING:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) auxiliary battery terminal to disable the SRS system.

    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 WIRE HARNESS (COMBINATION METER ASSEMBLY - BODY GROUND) 
    1. Connect the cable to the negative (-) auxiliary battery terminal.
      GTY838650Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Combination Meter Assembly)
    2. Turn the ignition switch to ON.
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      F23-21 (IG+) - Body ground Ignition switch ON 11 to 14 V
      F23-22 (B) - Body ground Always 11 to 14 V
    4. Turn the ignition switch off.
    5. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      F23-31 (ES) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE WIRE HARNESS 

    Result: 

    OK 

    See step  12

  12. CHECK SRS WARNING LIGHT 
    1. Disconnect the cable from the negative (-) auxiliary battery terminal.
      WARNING:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) auxiliary battery terminal to disable the SRS system.

    2. Connect the connector to the combination meter assembly.
    3. Connect the cable to the negative (-) auxiliary battery terminal.
    4. Turn the ignition switch to ON 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 ignition switch is turned to ON.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE AIRBAG ECU ASSEMBLY. Refer to  REMOVAL [10/2018 - 07/2022] 

    Result: 

    NG 

    REPLACE COMBINATION METER ASSEMBLY. Refer to  REMOVAL [10/2018 - 07/2022] 

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