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DTC C1380: Stop Light Control Relay Malfunction: Procedure

  1. INSPECT STOP LP RELAY 
    1. Remove the STOP LP relay from engine room relay block.
    2. Measure the resistance according to the value(s) in the table below.
      Fig 1: Identifying STOP LP Relay Terminals
      GTY301112Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Resistance

      Tester Connection Condition Specified Condition
      3 - 4 Battery voltage not applied Below 1 Ω
      Battery voltage applied to terminal 1 and 2 10 kΩ or higher
      3 - 5 Battery voltage not applied 10 kΩ or higher
      Battery voltage applied to terminal 1 and 2 Below 1 Ω

    NG → REPLACE STOP LP RELAY 

    OK: Go to next step 

  2. INSPECT STOP LP RELAY (ST+ TERMINAL) 
    1. Measure the voltage according to the value(s) in the table below.
      Fig 2: Measuring Voltage Of STOP LP Relay (ST+ Terminal)
      GTY300079Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Voltage

      Tester Connection Condition Specified Condition
      STOP LP relay-5(ST+) - Body ground Always 11 to 14 V
      TEXT IN ILLUSTRATION

      *1 Engine Room Relay Block
      *2 STOP LP Relay Holder

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  3. INSPECT STOP LP RELAY (STP TERMINAL) 
    1. Measure the voltage according to the value(s) in the table below.
      Fig 3: Measuring Voltage Of STOP LP Relay (ST+ Terminal)
      GTY300079Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Voltage

      Tester Connection Condition Specified Condition
      STOP LP relay-4(STP) - Body ground Brake pedal depressed 11 to 14 V
      STOP LP relay-4(STP) - Body ground Brake pedal released Below 1.5 V
      TEXT IN ILLUSTRATION

      *1 Engine Room Relay Block
      *2 STOP LP Relay Holder

    NG → See step   7 

    OK: Go to next step 

  4. INSPECT SKID CONTROL ECU (STP2 TERMINAL) 
    1. Install the STOP LP relay.
    2. Disconnect the A4 skid control ECU connector.
    3. Measure the voltage according to the value(s) in the table below.
      Fig 4: Inspecting Skid Control ECU (STP2 Terminal)
      GTY295803Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Voltage

      Tester Connection Condition Specified Condition
      A4-22 (STP2) - Body ground Brake pedal depressed 11 to 14 V
      A4-22 (STP2) - Body ground Brake pedal released Below 1.5 V
      TEXT IN ILLUSTRATION

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

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  5. INSPECT SKID CONTROL ECU (STP1 TERMINAL) 
    1. Measure the voltage according to the value(s) in the table below.
      Fig 5: Inspecting Skid Control ECU (STP1 Terminal)
      GTY307048Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Voltage

      Tester Connection Condition Specified Condition
      A4-2 (STP1) - Body ground Brake pedal depressed 11 to 14 V
      A4-2 (STP1) - Body ground Brake pedal released Below 1.5 V
      TEXT IN ILLUSTRATION

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

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  6. INSPECT SKID CONTROL ECU (STPO TERMINAL) 
    1. Measure the voltage according to the value(s) in the table below.
      Fig 6: Inspecting Skid Control ECU (STPO Terminal)
      GTY295802Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      A4-31 (STPO) - Body ground Ignition Switch ON 11 to 14 V
      TEXT IN ILLUSTRATION

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

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK → See step   11 

  7. CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY ASSEMBLY - STOP LP RELAY) 
    1. Disconnect the A43 stop light control relay Assembly
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Switch Condition Specified Condition
      STOP LP relay-4(STP) - A43-8(OUT) Always Below 1 Ω
      STOP LP relay-4(STP) - Body ground Always 10 kΩ or higher

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  8. INSPECT STOP LIGHT CONTROL RELAY ASSEMBLY (+B TERMINAL) 
    1. Measure the voltage according to the value(s) in the table below.
      Fig 7: Inspecting Stop Light Control Relay Assembly (+B Terminal)
      GTY305055Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Voltage

      Tester Connection Condition Specified Condition
      A43-6(+B) - Body ground Always 11 to 14 V
      TEXT IN ILLUSTRATION

      *a Front view of wire harness connector
      (to Stop Light Control Relay)

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  9. INSPECT STOP LIGHT CONTROL RELAY ASSEMBLY (GND TERMINAL) 
    1. Measure the resistance according to the value(s) in the table below.
      Fig 8: Inspecting Stop Light Control Relay Assembly (GND Terminal)
      GTY305056Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Resistance

      Tester Connection Condition Specified Condition
      A43-4(GND) - Body ground Always Below 1 Ω
      TEXT IN ILLUSTRATION

      *a Front view of wire harness connector
      (to Stop Light Control Relay)

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  10. INSPECT STOP LIGHT CONTROL RELAY ASSEMBLY (STP TERMINAL) 
    1. Measure the voltage according to the value(s) in the table below.
      Fig 9: Inspecting Stop Light Control Relay Assembly (STP Terminal)
      GTY305057Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Voltage

      Tester Connection Condition Specified Condition
      A43-2 (STP) - Body ground Brake pedal depressed 11 to 14 V
      A43-2 (STP) - Body ground Brake pedal released Below 1.5 V
      TEXT IN ILLUSTRATION

      *a Front view of wire harness connector
      (to Stop Light Control Relay)

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK → REPLACE STOP LIGHT CONTROL RELAY ASSEMBLY 

  11. REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL 
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