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DTC C1A4B: Stop Light Relay Circuit [03/2014 - ]: Procedure

  1. CHECK DTC OUTPUT (VSC SYSTEM) 
    1. Check for VSC system DTCs. Refer to DTC CHECK / CLEAR [03/2014 - ] .

      OK

      VSC system DTCs are not output.

    NG → See step   14 

    OK: Go to next step 

  2. 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

    NG → See step   16 

    OK: Go to next step 

  3. INSPECT STOP LIGHT SWITCH ASSEMBLY 
    1. Inspect the stop light switch assembly. Refer to ON-VEHICLE INSPECTION [03/2014 - ] .

      OK

      The stop light switch assembly is normal.

    NG → See step   15 

    OK: Go to next step 

  4. CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY ASSEMBLY POWER SOURCE) 
    1. Disconnect the stop light control relay assembly connector.
    2. Measure the voltage according to the value(s) in the table below.
      GTY461371Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Voltage

      Tester Connection Condition Specified Condition
      A52-6 (+B) - Body ground Always 11 to 14 V
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Stop Light Control Relay Assembly)
    3. Reconnect the stop light control relay assembly connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT CONTROL RELAY ASSEMBLY - STOP FUSE) 

    OK: Go to next step 

  5. CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY ASSEMBLY - BODY GROUND) 
    1. Disconnect the stop light control relay assembly connector.
    2. Measure the resistance according to the value(s) in the table below.
      GTY461370Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Resistance (Check for Open)

      Tester Connection Condition Specified Condition
      A52-8 (GND) - Body ground Always Below 1 Ω
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Stop Light Control Relay Assembly)
    3. Reconnect the stop light control relay assembly connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT CONTROL RELAY ASSEMBLY - BODY GROUND) 

    OK: Go to next step 

  6. CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY ASSEMBLY - STOP LIGHT SWITCH ASSEMBLY) 
    1. Turn the engine switch off.
    2. Disconnect the stop light control relay assembly connector.
    3. Measure the voltage according to the value(s) in the table below.
      GTY461366Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Voltage

      Tester Connection Condition Specified Condition
      A52-5 (STP) - Body ground Stop light switch ON
      (Brake pedal depressed)      		 11 to 14 V
      A52-5 (STP) - Body ground Stop light switch OFF
      (Brake pedal released)      		 Below 2 V
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Stop Light Control Relay Assembly)
    4. Reconnect the stop light control relay assembly connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT CONTROL RELAY ASSEMBLY- STOP LIGHT SWITCH ASSEMBLY) 

    OK: Go to next step 

  7. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - SKID CONTROL ECU) 
    1. Turn the engine 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 connector.
    4. Measure the voltage according to the value(s) in the table below.
      GTY470745Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Voltage

      Tester Connection Condition Specified Condition
      A44-22 (STP2) - Body ground Stop light switch ON
      (Brake pedal depressed)      		 11 to 14 V
      A44-22 (STP2) - Body ground Stop light switch OFF
      (Brake pedal released)      		 Below 1.5 V
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Skid Control ECU)
    5. Reconnect the skid control ECU connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - SKID CONTROL ECU) 

    OK: Go to next step 

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

      Tester Display Test Part Control Range Diagnostic Note
      Stop Light Relay Stop light control relay Relay ON/OFF Stop lights come on
    6. Select the Data List on the Techstream.
      ABS/VSC/TRAC

      Tester Display Test Part Control Range Diagnostic Note
      Stop Light Relay Output Stop light control relay output/
      ON or OFF      		 ON: Relay output on
      OFF: Relay output off      		 -
    7. Check stop light control relay assembly operation and stop light operation on the Data List while performing the Active Test.

      Result

      Result Proceed to
      Data List content and stop light operation are abnormal or Data List content is normal but stop lights do not turn on or off. A
      Data List content and stop light operation are normal. B
    8. Turn the engine switch off.

    B → See step   10 

    A: Go to next step 

  9. CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY ASSEMBLY - SKID CONTROL ECU) 
    1. Disconnect the stop light control relay assembly connector.
    2. Disconnect the skid control ECU connector.
    3. Measure the resistance according to the value(s) in the table below.
      GTY461560Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Resistance (Check for Open)

      Tester Connection Condition Specified Condition
      A52-9 (ACC) - A44-31 (STPO) Always Below 1 Ω

      Standard Resistance (Check for Short)

      Tester Connection Condition Specified Condition
      A52-9 (ACC) or A44-31 (STPO) - Body ground Always 10 kΩ or higher
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Skid Control ECU)
      *2 Front view of wire harness connector
      (to Stop Light Control Relay Assembly)
    4. Reconnect the stop light control relay assembly connector.
    5. Reconnect the skid control ECU connector.

    NG → See step   17 

    OK: Go to next step 

  10. CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY ASSEMBLY - SKID CONTROL ECU) 
    1. Disconnect the stop light control relay assembly connector.
    2. Disconnect the skid control ECU assembly connector.
    3. Measure the resistance according to the value(s) in the table below.
      GTY461561Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Resistance (Check for Open)

      Tester Connection Condition Specified Condition
      A52-5 (STP) - A44-2 (STP1) Always Below 1 Ω
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Skid Control ECU)
      *2 Front view of wire harness connector
      (to Stop Light Control Relay Assembly)
    4. Reconnect the stop light control relay assembly connector.
    5. Reconnect the skid control ECU connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT CONTROL RELAY ASSEMBLY - SKID CONTROL ECU) 

    OK: Go to next step 

  11. INSPECT STOP LIGHT CONTROL RELAY ASSEMBLY 
    1. Inspect the stop light control relay assembly. Refer to INSPECTION [03/2014 - ] .

    NG → REPLACE STOP LIGHT CONTROL RELAY ASSEMBLY 

    OK: Go to next step 

  12. CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY ASSEMBLY - SKID CONTROL ECU) 
    1. Turn the engine switch off.
    2. Disconnect the skid control ECU connector.
    3. Measure the voltage according to the value(s) in the table below.
      GTY466298Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Voltage

      Tester Connection Condition Specified Condition
      A44-2 (STP1) - Body ground Stop light switch ON
      (Brake pedal depressed)      		 11 to 14 V
      A44-2 (STP1) - Body ground Stop light switch OFF
      (Brake pedal released)      		 Below 1.5 V
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Skid Control ECU)
    4. Reconnect the skid control ECU connector.

    NG → See step   18 

    OK: Go to next step 

  13. CHECK DTC (DTC C1A4B) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Clear the DTCs. Refer to DTC CHECK / CLEAR [03/2014 - ] .
    4. Turn the Techstream on.
    5. Enter the following menus: Chassis / ABS/VSC/TRAC / Active Test.
    6. Select the Active Test on the Techstream.
      ABS/VSC/TRAC

      Tester Display Test Part Control Range Diagnostic Note
      Stop Light Relay Stop light control relay Relay ON/OFF Stop lights come on
    7. Select the Data List on the Techstream.
      ABS/VSC/TRAC

      Tester Display Test Part Control Range Diagnostic Note
      Stop Light Relay Output Stop light control relay output/
      ON or OFF      		 ON: Relay output on
      OFF: Relay output off      		 -
    8. Check stop light control relay assembly operation and stop light operation on the Data List while performing the Active Test.
    9. Recheck for DTCs. Refer to DTC CHECK / CLEAR [03/2014 - ] .

      Result

      Result Proceed to
      DTC is not output A
      DTC C1A4B is output B

    B → See step   19 

    A → END 

  14. GO TO VEHICLE STABILITY CONTROL SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [03/2014 - ] 
  15. REPLACE STOP LAMP SWITCH ASSEMBLY. Refer to  COMPONENTS [03/2014 - ] 
  16. GO TO LIGHTING SYSTEM (EXT). Refer to  PROBLEM SYMPTOMS TABLE [03/2014 - ] 
  17. REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT CONTROL RELAY ASSEMBLY - SKID CONTROL ECU). Refer to  COMPONENTS [03/2014 - ] 
  18. REPLACE STOP LIGHT CONTROL RELAY ASSEMBLY. Refer to  COMPONENTS [03/2014 - ] 
  19. REPLACE DRIVING SUPPORT ECU. Refer to  COMPONENTS [03/2014 - ] 
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