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Home >> Lexus >> 2015 >> ES 350 >> Repair and Diagnosis (Single Page) >> Restraints >> Restraints Control Systems >> Pre-Collision - Diagnostic Codes & Circuit Tests >> Pre-Collision System >> DTC C1A4B: Stop Light Relay Circuit [08/2014 - ] >> Procedure

DTC C1A4B: Stop Light Relay Circuit [08/2014 - ]: Procedure

  1. CHECK DTC OUTPUT (VSC SYSTEM) 
    1. Check for VSC system DTCs. Refer to DTC CHECK / CLEAR [08/2014 - ] .

      OK

      VSC system DTCs are not output.

    NG → See step   12 

    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   14 

    OK: Go to next step 

  3. INSPECT ENGINE ROOM JUNCTION BLOCK ASSEMBLY 
    1. Turn the engine switch off.
    2. Check the Engine room junction block assembly. Refer to ON-VEHICLE INSPECTION [08/2014 - ] .

      OK

      The Engine room junction block assembly is normal.

    NG → REPAIR OR REPLACE WIRE HARNESS OR ENGINE ROOM JUNCTION BLOCK ASSEMBLY 

    OK: Go to next step 

  4. CHECK HARNESS AND CONNECTOR (STP TERMINAL) 
    1. Turn the engine switch off.
      GTY414775Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Make sure that there is no looseness at the locking part and the connecting part of the connector.
    3. Disconnect the A40 skid control ECU (brake actuator) connector.
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A40-2 (STP) - Body ground Stop light switch assembly ON (Brake pedal depressed) 11 to 14 V
      A40-2 (STP) - Body ground Stop light switch assembly OFF (Brake pedal released) Below 1.5 V
      TEXT IN ILLUSTRATION

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

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (STP CIRCUIT) 

    OK: Go to next step 

  5. CHECK HARNESS AND CONNECTOR (STPS TERMINAL) 
    1. Disconnect the 1F Engine room junction block assembly connector.
      GTY404570Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      1F-16 (STPS) - Body ground Stop light switch assembly ON (Brake pedal depressed) 11 to 14 V
      1F-16 (STPS) - Body ground Stop light switch assembly OFF (Brake pedal released) Below 1.5 V
      TEXT IN ILLUSTRATION

      *a Front view of wire harness connector
      (to Engine room junction block assembly (Engine Room Junction Block Assembly))

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (STPS CIRCUIT) 

    OK: Go to next step 

  6. PERFORM ACTIVE TEST USING TECHSTREAM (STOP LIGHT RELAY) 
    1. Select the Active Test on the Techstream. Refer to DATA LIST / ACTIVE TEST [08/2014 - ] .
      ABS/VSC/TRAC

      Tester Display Test Part Control Range Diagnostic Note
      Stop Light Relay Engine room junction block assembly Relay ON/OFF Stop lights come on
    2. Perform the Active Test of the Engine room junction block assembly using the Techstream.
    3. Select the Data List on the Techstream. Refer to DATA LIST / ACTIVE TEST [08/2014 - ] .
      ABS/VSC/TRAC

      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Stop Light Relay Output Engine room junction block assembly output / ON or OFF ON: Relay output on
      OFF: Relay output off      		 -
    4. Check for Engine room junction block assembly operation using the Data List and stop light operation by performing an 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

    B → See step   8 

    A: Go to next step 

  7. CHECK HARNESS AND CONNECTOR (ENGINE ROOM JUNCTION BLOCK - BRAKE ACTUATOR ASSEMBLY) 
    1. Turn the engine switch off.
    2. Remove the engine room junction block assembly from the engine room relay block and junction block assembly
    3. Disconnect the A40 skid control ECU (brake actuator assembly) connector.
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      1G-3 (ACC) - A40-31 (STPO) Always Below 1 Ω
      1G-3 (ACC) or A40-31 (STPO) - Body ground Always 10 kΩ or higher

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  8. CHECK HARNESS AND CONNECTOR (ENGINE ROOM JUNCTION BLOCK - BRAKE ACTUATOR ASSEMBLY) 
    1. Turn the engine switch off.
    2. Remove the engine room junction block assembly from the engine room relay block and junction block assembly
    3. Disconnect the A40 skid control ECU (brake actuator assembly) connector.
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      1F-11 (STOP) - A40-22 (STP2) Always Below 1 Ω

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  9. CHECK HARNESS AND CONNECTOR (STP2 TERMINAL) 
    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.
      GTY408368Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    3. Disconnect the A40 skid control ECU (brake actuator assembly) connector.
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A40-22 (STP2) - Body ground Stop light switch ON (Brake pedal depressed) 11 to 14 V
      A40-22 (STP2) - Body ground Stop light switch OFF (Brake pedal released) Below 1.5 V
      TEXT IN ILLUSTRATION

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

    NG → See step   13 

    OK: Go to next step 

  10. CHECK DTC OUTPUT (PRE-COLLISION SYSTEM) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream on.
    4. Enter the following menus: Body Electrical / Pre-Collision 2 / Trouble Codes.
    5. Clear the DTCs. Refer to DTC CHECK / CLEAR [08/2014 - ] .
    6. Select the Active Test on the Techstream. Refer to DATA LIST / ACTIVE TEST [08/2014 - ] .
      ABS/VSC/TRAC

      Tester Display Test Part Control Range Diagnostic Note
      Stop Light Relay Engine room junction block assembly Relay ON/OFF Stop lights come on
    7. Perform the Active Test of the Engine room junction block assembly using the Techstream.
    8. Select the Data List on the Techstream. Refer to DATA LIST / ACTIVE TEST [08/2014 - ] .
      ABS/VSC/TRAC

      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Stop Light Relay Output Engine room junction block assembly output / ON or OFF ON: Relay output on
      OFF: Relay output off      		 -
    9. Check for Engine room junction block assembly operation using the Data List and stop light operation by performing an Active Test.
    10. Recheck for DTCs.

      OK

      DTC C1A4B is not output.

    NG → See step   11 

    OK → END 

  11. REPLACE DRIVING SUPPORT ECU ASSEMBLY. Refer to  COMPONENTS [08/2014 - ] 
  12. GO TO VEHICLE STABILITY CONTROL SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [08/2014 - ] 
  13. REPLACE ENGINE ROOM JUNCTION BLOCK ASSEMBLY. Refer to  COMPONENTS [08/2014 - ] 
  14. INSPECT LIGHTING SYSTEM (STOP LIGHT CIRCUIT). Refer to  PROBLEM SYMPTOMS TABLE [08/2014 - ] 
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