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Home >> Lexus >> 2017 >> GS 450h Base >> Repair and Diagnosis (Single Page) >> Restraints >> Restraints Control Systems >> Pre-Collision System (Diagnostic Codes & Circuit Tests) >> Pre-Collision System >> DTC C1A4B: Stop Light Relay Circuit [09/2014 - 10/2015] >> Procedure

DTC C1A4B: Stop Light Relay Circuit [09/2014 - 10/2015]: Procedure

  1. CHECK STOP LIGHT OPERATION 
    1. Check that the stop lights come on when the brake pedal is depressed, and go off when the brake pedal is released.

      OK

      Condition Illumination Condition
      Brake pedal depressed ON
      Brake pedal released OFF

    Result:  NG

    NG 

    GO TO LIGHTING SYSTEM 

    (See page. Refer to HOW TO PROCEED WITH TROUBLESHOOTING [09/2014 - 10/2015] )

    Result:  OK

    OK 

    See step  2

  2. CHECK HARNESS AND CONNECTOR (NO. 2 INTEGRATION RELAY POWER SOURCE TERMINAL) 
    1. Turn the power switch off.
      GTY536244Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the No. 2 integration relay connectors.
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      1B-7 (BATT) - Body ground Always 11 to 14 V
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      1A-22 (GNDA) - Body ground Always Below 1 Ω
      1B-10 (GNDB) - Body ground Always Below 1 Ω
      TEXT IN ILLUSTRATION

      *a Front view of wire harness connector
      (to No. 2 Integration Relay)

    Result:  NG

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result:  OK

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (STP TERMINAL) 
    1. Turn the power switch off.
    2. Make sure that there is no looseness at the locking part and the connecting part of the connector.
      GTY531210Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    3. Disconnect the skid control ECU assembly connector.
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A16-25 (STP) - Body ground Brake pedal depressed 11 to 14 V
      Brake pedal released Below 1.5 V
      TEXT IN ILLUSTRATION

      *a Front view of wire harness connector
      (to Skid Control ECU Assembly)

    Result:  NG

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result:  OK

    OK 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (BATTERY - NO. 2 INTEGRATION RELAY) 
    1. Turn the power switch off.
    2. Disconnect the No. 2 integration relay connector.
      GTY537726Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      1A-11 (STP0) - Body ground Brake pedal depressed 11 to 14 V
      Brake pedal released Below 1.5 V
      TEXT IN ILLUSTRATION

      *a Front view of wire harness connector
      (to No. 2 Integration Relay)

    Result:  NG

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result:  OK

    OK 

    See step  5

  5. PERFORM ACTIVE TEST USING TECHSTREAM (STOP LIGHT RELAY) 
    1. Turn the power switch off.
    2. Connect the Techstream to the DLC3.
    3. Start the engine.
    4. Turn the Techstream on.
    5. Enter the following menus: Chassis / ABS/VSC/TRAC / Active Test.
      ABS/VSC/TRAC

      Tester Display Test Part Control Range Diagnostic Note
      Stop Light Relay No. 2 integration relay ON / OFF Stop lights come on
    6. While performing the Active Test, check the illumination condition of the stop lights and "Stop Light Relay Output" in the Data List.
      ABS/VSC/TRAC

      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Stop Light Relay No. 2 integration relay output / ON or OFF ON: Relay output on
      OFF: Relay output off      		 -
      RESULT

      Result Proceed to
      When Active Test performed, Data List item changes between ON and OFF, but stop lights do not turn on A
      When Active Test performed, Data List item changes between ON and OFF and stop lights turn on and off B

    Result:  B

    B 

    See step  7

    Result:  A

    A 

    See step  6

  6. CHECK HARNESS AND CONNECTOR (NO. 2 INTEGRATION RELAY - SKID CONTROL ECU ASSEMBLY) 
    1. Turn the power switch off.
    2. Disconnect the 1A No. 2 integration relay connector.
    3. Disconnect the A16 skid control ECU assembly connector.
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      1A-7 (ACC) - A16-31 (STPO) Always Below 1 Ω
      1A-7 (ACC) - Body ground Always 10 kΩ or higher

    Result:  NG

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result:  OK

    OK 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (NO. 2 INTEGRATION RELAY - SKID CONTROL ECU ASSEMBLY) 
    1. Turn the power switch off.
    2. Disconnect the 1A No. 2 integration relay connector.
    3. Disconnect the A14 skid control ECU assembly connector.
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      1A-3 (STOP) - A14-24 (STP2) Always Below 1 Ω
      1A-3 (STOP) - Body ground Always 10 kΩ or higher

    Result:  NG

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result:  OK

    OK 

    See step  8

  8. CHECK HARNESS AND CONNECTOR (STP2 TERMINAL) 
    1. Turn the power switch off.
    2. Make sure that there is no looseness at the locking part and the connecting part of the connector.
    3. Disconnect the skid control ECU assembly connector.
      GTY525326Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A14-24 (STP2) - Body ground Brake pedal depressed 11 to 14 V
      Brake pedal released Below 1.5 V
      TEXT IN ILLUSTRATION

      *a Front view of wire harness connector
      (to Skid Control ECU Assembly)

    Result:  NG

    NG 

    REPLACE NO. 2 INTEGRATION RELAY 

    (See page. Refer to REMOVAL [09/2014 - ] )

    Result:  OK

    OK 

    See step  9

  9. CHECK FOR DTC 
    1. Turn the power switch off and wait for at least 2 minutes.
    2. Clear the DTCs (See page. Refer to DTC CHECK / CLEAR [09/2014 - 10/2015] ).
    3. Make sure that the DTC detection conditions are met.

      HINT: 

      If the detection conditions are not met, the system cannot detect the malfunction.

      • Using the Techstream, perform the Active Test "Stop Light Relay" with the power switch on (IG).
    4. Check for DTCs (See page. Refer to DTC CHECK / CLEAR [09/2014 - 10/2015] ).
      NOTE:

      When replacing the driving support ECU, always replace it with a new one and be sure to perform initialization (See page. Refer to INITIALIZATION [09/2014 - 10/2015] ). If an ECU which was installed to another vehicle is used, the information stored in the ECU will not match the information from the vehicle, and as a result, a DTC may be stored.

      OK

      DTC C1A4B is not output.

    Result:  OK

    OK 

    END 

    Result:  NG

    NG 

    REPLACE DRIVING SUPPORT ECU 

    (See page. Refer to REMOVAL [09/2014 - 10/2015] )

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