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DTC C1A4B: Stop Light Relay Circuit [10/2014 - 09/2017]: Procedure

  1. CHECK TERMINAL VOLTAGE (STP, STPO AND STP2 TERMINAL) 
    1. Turn the power swich off.
    2. Disconnect the brake booster with master cylinder assembly (skid control ECU) connector.
      GTY675710Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Brake Booster with Master Cylinder Assembly [Skid Control ECU])
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A57-6 (STP2) - Body ground Brake pedal depressed 11 to 14 V
      Brake pedal released Below 1.5 V
      A57-3 (STPO) - Body ground Always 11 to 14 V
      A57-33 (STP) - Body ground Brake pedal depressed 11 to 14 V
      Brake pedal released Below 1.5 V

      Result

      Result Proceed to
      All terminal voltage is normal A
      Only STP terminal voltage abnormal B
      Only STPO terminal voltage abnormal C
      Only STP2 terminal voltage abnormal D
      STPO terminal and STP2 terminal voltage abnormal E

    Result: 

    B 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    C 

    See step  5

    Result: 

    D 

    See step  6

    Result: 

    E 

    See step  16

    Result: 

    A 

    See step  2

  2. PERFORM ACTIVE TEST USING TECHSTREAM (STOP LIGHT RELAY) 
    1. Enter the following menus: Chassis / ABS/VSC/TRAC / Active Test.
    2. Perform "Active Test" according to the display on the Techstream.

      Chassis > ABS/VSC/TRAC > Active Test 

      Tester Display Measurement Item Control Range Diagnostic Note
      Stop Light Relay Stop light control ECU assembly (stop light control relay) ECU (Relay) ON/OFF Stop lights come on

      Chassis > ABS/VSC/TRAC > Active Test 

      Tester Display
      Stop Light Relay

      OK

      Stop light turns ON/OFF in response to the Techstream operation

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  4

    Result: 

    OK 

    See step  3

  3. CHECK FOR DTC 
    1. Clear the DTCs.

      Refer to DTC CHECK / CLEAR [10/2014 - 09/2017]

      Body Electrical > Pre-Collision 2 > Clear DTCs 

    2. Enter the following menus: Chassis / ABS/VSC/TRAC / Active Test.
    3. Perform "Active Test" according to the display on the Techstream.

      Chassis > ABS/VSC/TRAC > Active Test 

      Tester Display Measurement Item Control Range Diagnostic Note
      Stop Light Relay Stop light control ECU assembly (stop light control relay) ECU (Relay) ON/OFF Stop lights come on

      Chassis > ABS/VSC/TRAC > Active Test 

      Tester Display
      Stop Light Relay
    4. Check for DTCs.

      Refer to DTC CHECK / CLEAR [10/2014 - 09/2017]

      Body Electrical > Pre-Collision 2 > Trouble Codes 

      Result

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

    Result: 

    A 

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SKID CONTROL ECU). Refer to  REMOVAL [10/2014 - 09/2015]  , or refer to  REMOVAL [09/2015 - 05/2019] 

    Result: 

    B 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [10/2014 - 09/2017] 

  4. INSPECT BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SKID CONTROL ECU) 
    1. Enter the following menus: Chassis / ABS/VSC/TRAC / Active Test.
    2. Perform "Active Test" according to the display on the Techstream.

      Chassis > ABS/VSC/TRAC > Active Test 

      Tester Display Measurement Item Control Range Diagnostic Note
      Stop Light Relay Stop light control ECU assembly (stop light control relay) ECU (Relay) ON/OFF Stop lights come on

      Chassis > ABS/VSC/TRAC > Active Test 

      Tester Display
      Stop Light Relay
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A3-9 (ACC) - Body ground Active test is ON Below 1.5 V
      GTY643071Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Stop Light Control ECU Assembly)

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE STOP LIGHT CONTROL ECU ASSEMBLY. Refer to  REMOVAL [10/2014 - ] 

    Result: 

    NG 

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SKID CONTROL ECU). Refer to  REMOVAL [10/2014 - 09/2015]  , or refer to  REMOVAL [09/2015 - 05/2019] 

  5. CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY [SKID CONTROL ECU] - STOP LIGHT CONTROL ECU ASSEMBLY) 
    1. Turn the power switch off.
    2. Disconnect the A57 brake booster with master cylinder assembly (skid control ECU) connector.
    3. Disconnect the A3 stop light control ECU assembly connector.
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A57-3 (STPO) - A3-9 (ACC) Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE STOP LIGHT CONTROL ECU ASSEMBLY. Refer to  REMOVAL [10/2014 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  6. CHECK TERMINAL VOLTAGE (STP2 TERMINAL) 
    1. Turn the power switch off.
    2. Disconnect the brake booster with master cylinder assembly (skid control ECU) connector.
      GTY627098Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Brake Booster with Master Cylinder Assembly [Skid Control ECU])
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A57-6 (STP2) - Body ground Brake pedal released Below 1.5 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  10

    Result: 

    OK 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY [SKID CONTROL ECU] - REAR COMBINATION LIGHT ASSEMBLY LH) 
    1. Turn the power switch off.
    2. Disconnect the A57 brake booster with master cylinder assembly (skid control ECU) connector.
    3. Disconnect the Q16 rear combination light assembly LH connector.
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A57-6 (STP2) - Body ground Brake pedal depressed 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE REAR COMBINATION LIGHT ASSEMBLY LH. Refer to  REMOVAL [10/2014 - 09/2017] 

    Result: 

    NG 

    See step  8

  8. CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY [SKID CONTROL ECU] - REAR COMBINATION LIGHT ASSEMBLY RH) 
    1. Turn the power switch off.
    2. Disconnect the A57 brake booster with master cylinder assembly (skid control ECU) connector.
    3. Disconnect the Q16 rear combination light assembly LH connector.
    4. Disconnect the P13 rear combination light assembly RH connector.
    5. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A57-6 (STP2) - Body ground Brake pedal depressed 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE REAR COMBINATION LIGHT ASSEMBLY RH. Refer to  REMOVAL [10/2014 - 09/2017] 

    Result: 

    NG 

    See step  9

  9. CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY [SKID CONTROL ECU] - REAR LIGHT ASSEMBLY LH) 
    1. Turn the power switch off.
    2. Disconnect the A57 brake booster with master cylinder assembly (skid control ECU) connector.
    3. Disconnect the Q16 rear combination light assembly LH connector.
    4. Disconnect the P13 rear combination light assembly RH connector.
    5. Disconnect the Y11 rear light assembly LH connector.
    6. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A57-6 (STP2) - Body ground Brake pedal depressed 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE REAR LIGHT ASSEMBLY LH. Refer to  REMOVAL [10/2014 - 09/2017] 

    Result: 

    NG 

    See step  11

  10. CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY [SKID CONTROL ECU] - STOP LIGHT CONTROL ECU ASSEMBLY) 
    1. Turn the power switch off.
    2. Disconnect the A57 brake booster with master cylinder assembly (skid control ECU) connector.
    3. Disconnect the A3 stop light control ECU assembly connector.
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A57-6 (STP2) - Body ground Brake pedal released Below 1.5 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE STOP LIGHT CONTROL ECU ASSEMBLY. Refer to  REMOVAL [10/2014 - ] 

    Result: 

    NG 

    See step  12

  11. CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY [SKID CONTROL ECU] - REAR LIGHT ASSEMBLY RH) 
    1. Turn the power switch off.
    2. Disconnect the A57 brake booster with master cylinder assembly (skid control ECU) connector.
    3. Disconnect the Q16 rear combination light assembly LH connector.
    4. Disconnect the P13 rear combination light assembly RH connector.
    5. Disconnect the Y11 rear light assembly LH connector.
    6. Disconnect the Y10 rear light assembly RH connector.
    7. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A57-6 (STP2) - Body ground Brake pedal depressed 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE REAR LIGHT ASSEMBLY RH. Refer to  REMOVAL [10/2014 - 09/2017] 

    Result: 

    NG 

    See step  13

  12. CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY [SKID CONTROL ECU] - REAR COMBINATION LIGHT ASSEMBLY LH) 
    1. Turn the power switch off.
    2. Disconnect the A57 brake booster with master cylinder assembly (skid control ECU) connector.
    3. Disconnect the A3 stop light control ECU assembly connector.
    4. Disconnect the Q16 rear combination light assembly LH connector.
    5. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A57-6 (STP2) - Body ground Brake pedal released Below 1.5 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE REAR COMBINATION LIGHT ASSEMBLY LH. Refer to  REMOVAL [10/2014 - 09/2017] 

    Result: 

    NG 

    See step  14

  13. CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY [SKID CONTROL ECU] - CENTER STOP LIGHT ASSEMBLY) 
    1. Turn the power switch off.
    2. Disconnect the A57 brake booster with master cylinder assembly (skid control ECU) connector.
    3. Disconnect the Q16 rear combination light assembly LH connector.
    4. Disconnect the P13 rear combination light assembly RH connector.
    5. Disconnect the Y11 rear light assembly LH connector.
    6. Disconnect the Y10 rear light assembly RH connector.
    7. Disconnect the e1 center stop light assembly connector.
    8. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A57-6 (STP2) - Body ground Brake pedal depressed 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE CENTER STOP LIGHT ASSEMBLY. Refer to  REMOVAL [10/2014 - ] 

    Result: 

    NG 

    See step  15

  14. CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY [SKID CONTROL ECU] - REAR COMBINATION LIGHT ASSEMBLY RH) 
    1. Turn the power switch off.
    2. Disconnect the A57 brake booster with master cylinder assembly (skid control ECU) connector.
    3. Disconnect the A3 stop light control ECU assembly connector.
    4. Disconnect the Q16 rear combination light assembly LH connector.
    5. Disconnect the P13 rear combination light assembly RH connector.
    6. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A57-6 (STP2) - Body ground Brake pedal released Below 1.5 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE REAR COMBINATION LIGHT ASSEMBLY RH. Refer to  REMOVAL [10/2014 - 09/2017] 

    Result: 

    NG 

    See step  18

  15. CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY [SKID CONTROL ECU] - STOP LIGHT CONTROL ECU ASSEMBLY) 
    1. Turn the power switch off.
    2. Disconnect the A57 brake booster with master cylinder assembly (skid control ECU) connector.
    3. Disconnect the Q16 rear combination light assembly LH connector.
    4. Disconnect the P13 rear combination light assembly RH connector.
    5. Disconnect the Y11 rear light assembly LH connector.
    6. Disconnect the Y10 rear light assembly RH connector.
    7. Disconnect the e1 center stop light assembly connector.
    8. Disconnect the A3 stop light control ECU assembly connector.
    9. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A3-5 (STP) - A57-33 (STP) Always Below 1 Ω
      A3-1 (OUT) - A57-6 (STP2) Always Below 1 Ω
      A3-1 (OUT) or A57-6 (STP2) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE STOP LIGHT CONTROL ECU ASSEMBLY. Refer to  REMOVAL [10/2014 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  16. CHECK STOP LIGHT CONTROL ECU ASSEMBLY POWER SOURCE CIRCUIT 
    1. Turn the power switch off.
    2. Disconnect the stop light control ECU assembly connector.
      GTY651318Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Stop Light Control ECU Assembly)
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A3-8 (GND) - Body ground Always Below 1 Ω
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      A3-6 (+B) - Body ground Power swich off 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  17

  17. CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY [SKID CONTROL ECU] - STOP LIGHT CONTROL ECU ASSEMBLY) 
    1. Turn the power switch off.
    2. Disconnect the A57 brake booster with master cylinder assembly (skid control ECU) connector.
    3. Disconnect the A3 stop light control ECU assembly connector.
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A57-3 (STPO) - A3-9 (ACC) Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE STOP LIGHT CONTROL ECU ASSEMBLY. Refer to  REMOVAL [10/2014 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  18. CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY [SKID CONTROL ECU] - REAR LIGHT ASSEMBLY LH) 
    1. Turn the power switch off.
    2. Disconnect the A57 brake booster with master cylinder assembly (skid control ECU) connector.
    3. Disconnect the A3 stop light control ECU assembly connector.
    4. Disconnect the Q16 rear combination light assembly LH connector.
    5. Disconnect the P13 rear combination light assembly RH connector.
    6. Disconnect the Y11 rear light assembly LH connector.
    7. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A57-6 (STP2) - Body ground Brake pedal released Below 1.5 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE REAR LIGHT ASSEMBLY LH. Refer to  REMOVAL [10/2014 - 09/2017] 

    Result: 

    NG 

    See step  19

  19. CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY [SKID CONTROL ECU] - REAR LIGHT ASSEMBLY RH) 
    1. Turn the power switch off.
    2. Disconnect the A57 brake booster with master cylinder assembly (skid control ECU) connector.
    3. Disconnect the A3 stop light control ECU assembly connector.
    4. Disconnect the Q16 rear combination light assembly LH connector.
    5. Disconnect the P13 rear combination light assembly RH connector.
    6. Disconnect the Y11 rear light assembly LH connector.
    7. Disconnect the Y10 rear light assembly RH connector.
    8. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A57-6 (STP2) - Body ground Brake pedal released Below 1.5 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE REAR LIGHT ASSEMBLY RH. Refer to  REMOVAL [10/2014 - 09/2017] 

    Result: 

    NG 

    See step  20

  20. CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY [SKID CONTROL ECU] - CENTER STOP LIGHT ASSEMBLY) 
    1. Turn the power switch off.
    2. Disconnect the A57 brake booster with master cylinder assembly (skid control ECU) connector.
    3. Disconnect the A3 stop light control ECU assembly connector.
    4. Disconnect the Q16 rear combination light assembly LH connector.
    5. Disconnect the P13 rear combination light assembly RH connector.
    6. Disconnect the Y11 rear light assembly LH connector.
    7. Disconnect the Y10 rear light assembly RH connector.
    8. Disconnect the e1 center stop light assembly connector.
    9. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A57-6 (STP2) - Body ground Brake pedal released Below 1.5 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE CENTER STOP LIGHT ASSEMBLY. Refer to  REMOVAL [10/2014 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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