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DTC C1A4B: Stop Light Relay Circuit [11/2017 - ]: Procedure

  1. INSPECT TERMINAL VOLTAGE (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) CONNECTOR) 
    1. Turn the ignition switch off.
    2. Disconnect the skid control ECU (brake actuator assembly) connector.
      GTY756557Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Skid Control ECU (Brake Actuator Assembly))
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A75-5 (STP2) - Body ground Brake pedal depressed 8 to 14 V
      Brake pedal released Below 1.5 V
      A75-26 (STPO) - Body ground Ignition switch ON 11 to 14 V
      A75-35 (STP) - Body ground Brake pedal depressed 8 to 14 V
      Brake pedal released Below 1.5 V
    4. Connect the A75 skid control ECU (brake actuator assembly) connector.

      Result

      Result Proceed to
      The voltage is as specified for every terminal. A
      Only the voltage at terminal STPO is not as specified. B
      Only the voltage at terminal STP is not as specified. C
      Only the voltage at terminal STP2 is not as specified. D
      The voltage at both terminal STPO and terminal STP are not as specified. E

    Result: 

    B 

    See step  5

    Result: 

    C 

    See step  7

    Result: 

    D 

    See step  11

    Result: 

    E 

    See step  12

    Result: 

    A 

    See step  2

  2. PERFORM ACTIVE TEST USING TECHSTREAM (STOP LIGHT RELAY) 
    1. Turn the ignition switch off.
    2. According to the display on the Techstream, perform the Active Test Stop Light Relay.

      Refer to DATA LIST / ACTIVE TEST [11/2017 - ]

      ABS/VSC/TRAC

      Tester Display Test Part Control Range Diagnostic Note
      Stop Light Relay Stop light relay (Stop light switch assembly) ON/OFF Test possible at vehicle speed of 0 km/h (0 mph)

      OK

      The stop lights turn on and off correctly in response to the operation of the Active Test.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  4

    Result: 

    OK 

    See step  3

  3. CHECK FOR DTCS (PRE-COLLISION SYSTEM) 
    1. Clear the DTCs.

      Refer to DTC CHECK / CLEAR [11/2017 - ]

    2. According to the display on the Techstream, perform the Active Test Stop Light Relay.

      Refer to DATA LIST / ACTIVE TEST [11/2017 - ]

      ABS/VSC/TRAC

      Tester Display Test Part Control Range Diagnostic Note
      Stop Light Relay Stop light relay (Stop light switch assembly) ON/OFF Test possible at vehicle speed of 0 km/h (0 mph)
    3. Check for DTCs.

      Refer to DTC CHECK / CLEAR [11/2017 - ]

      OK

      DTC C1A4B is not output.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [11/2017 - ] 

    Result: 

    NG 

    REPLACE BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU). Refer to  COMPONENTS [11/2017 - ] 

  4. INSPECT STOP LP RELAY 
    1. Remove the STOP LP relay from No. 3 engine relay block.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      3 - 4 Voltage is not applied between terminals 1 and 2 Below 1 Ω
      3 - 4 Voltage is applied between terminals 1 and 2 10 kΩ or higher
      GTY773567Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 STOP LP Relay

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU). Refer to  COMPONENTS [11/2017 - ] 

    Result: 

    NG 

    REPLACE STOP LP RELAY 

  5. CHECK WIRE HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU) - STOP LIGHT LP RELAY) 
    1. Turn the ignition switch off.
    2. Remove the STOP LP relay from No. 3 engine room relay block.
      GTY761963Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a No. 3 Engine Room Relay Block (Relay Holder)
    3. Disconnect the A75 brake actuator assembly (skid control ECU) connector.
      GTY756558Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Brake actuator assembly (skid control ECU))
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A75-26 (STPO) - Relay holder terminal 1 Always Below 1 Ω
      A75-26 (STPO) or Relay holder terminal 1 - Body ground Always 10 kΩ or higher
    5. Reconnect the A75 brake actuator assembly (skid control ECU) connector.
    6. Install the STOP LP relay to the No. 3 engine room relay block.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  6

  6. INSPECT STOP LP RELAY (POWER SOURCE CIRCUIT) 
    1. Turn the ignition switch off.
    2. Remove the STOP LP relay from the No. 3 engine room relay block.
      GTY761962Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a No. 3 Engine Room Relay Block (Relay Holder)
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      Relay holder terminal 2 - Body ground Ignition switch ON 11 to 14 V
      Relay holder terminal 5 - Body ground Always 11 to 14 V
    4. Install the STOP LP relay to the No. 3 engine room relay block.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE STOP LP RELAY 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  7. INSPECT STOP LP RELAY 
    1. Remove the STOP LP relay from No. 3 engine relay block.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      3 - 4 Voltage is not applied between terminals 1 and 2 Below 1 Ω
      3 - 4 Voltage is applied between terminals 1 and 2 10 kΩ or higher
      GTY773567Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 STOP LP Relay

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE STOP LP RELAY 

    Result: 

    OK 

    See step  8

  8. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) - REAR COMBINATION LIGHT ASSEMBLY LH) 
    1. for Bulb Type Stop Light
      1. Turn the ignition switch off.
      2. Disconnect the A75 brake actuator assembly (skid control ECU) connector.
      3. Disconnect the K35 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
        A75-35 (STP) or K35-3 (B) - Body ground Brake pedal depressed 8 to 14 V
      5. Reconnect the K35 rear combination light assembly LH connector.
      6. Reconnect the A75 brake actuator assembly (skid control ECU) connector.
    2. for LED Type Stop Light
      1. Turn the ignition switch off.
      2. Disconnect the A75 brake actuator assembly (skid control ECU) connector.
      3. Disconnect the K18 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
        A75-35 (STP) or K18-4 (B) - Body ground Brake pedal depressed 8 to 14 V
      5. Reconnect the K18 rear combination light assembly LH connector.
      6. Reconnect the A75 brake actuator assembly (skid control ECU) connector.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE REAR COMBINATION LIGHT ASSEMBLY LH. Refer to  REMOVAL [12/2015 - ] 

    Result: 

    NG 

    See step  9

  9. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) - CENTER STOP LIGHT ASSEMBLY) 
    1. Turn the ignition switch off.
    2. Disconnect the A75 skid control ECU (brake actuator assembly) connector.
    3. Disconnect the m1 center stop light assembly connector.
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A75-35 (STP) or m1-2 (STP) - Body ground Brake pedal depressed 8 to 14 V
    5. Connect the m1 center stop light assembly connector.
    6. Connect the A75 skid control ECU (brake actuator assembly) connector.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE CENTER STOP LIGHT ASSEMBLY. Refer to  REMOVAL [12/2015 - ] 

    Result: 

    NG 

    See step  10

  10. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) - REAR COMBINATION LIGHT ASSEMBLY RH) 
    1. for Bulb Type Stop Light
      1. Turn the ignition switch off.
      2. Disconnect the A75 brake actuator assembly (skid control ECU) connector.
      3. Disconnect the L52 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
        A75-35 (STP) or L52-3 (B) - Body ground Brake pedal depressed 8 to 14 V
      5. Reconnect the L52 rear combination light assembly LH connector.
      6. Reconnect the A75 brake actuator assembly (skid control ECU) connector.
    2. for LED Type Stop Light
      1. Turn the ignition switch off.
      2. Disconnect the A75 brake actuator assembly (skid control ECU) connector.
      3. Disconnect the L33 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
        A75-35 (STP) or L33-4 (B) - Body ground Brake pedal depressed 8 to 14 V
      5. Reconnect the L33 rear combination light assembly LH connector.
      6. Reconnect the A75 brake actuator assembly (skid control ECU) connector.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE REAR COMBINATION LIGHT ASSEMBLY RH. Refer to  REMOVAL [12/2015 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  11. INSPECT STOP LP RELAY 
    1. Remove the STOP LP relay from No. 3 engine relay block.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      3 - 4 Voltage is not applied between terminals 1 and 2 Below 1 Ω
      3 - 4 Voltage is applied between terminals 1 and 2 10 kΩ or higher
      GTY773567Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 STOP LP Relay

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    NG 

    REPLACE STOP LP RELAY 

  12. CHECK WIRE HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU) - STOP LIGHT LP RELAY) 
    1. Turn the ignition switch off.
    2. Remove the STOP LP relay from No. 3 engine room relay block.
      GTY761963Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a No. 3 Engine Room Relay Block (Relay Holder)
    3. Disconnect the A75 brake actuator assembly (skid control ECU) connector.
      GTY772064Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Brake actuator assembly (skid control ECU))
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A75-26 (STPO) - Relay holder terminal 1 Always Below 1 Ω
    5. Reconnect the A75 brake actuator assembly (skid control ECU) connector.
    6. Install the STOP LP relay to the No. 3 engine room relay block.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE STOP LP RELAY 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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