PRE-COLLISION SYSTEM, Diagnostic DTC:C1A4B

DTC Code DTC Name
C1A4B Stop Light Relay Circuit

DESCRIPTION

The skid control ECU (brake actuator assembly) sends a stop light operation request signal to the stop light relay (stop light switch assembly). If the skid control ECU (brake actuator assembly) detects a malfunction in the stop light relay circuit, the driving support ECU assembly stores DTC C1A4B.

DTC No. DTC Detection Condition Trouble Area
C1A4B

  • All of the following conditions are met:


    • 3 seconds have elapsed since the ignition switch was turned ON.

    • The battery voltage is 10 V or more for 3 seconds or more.

    • Communication between the pre-collision city sensor and skid control ECU (brake actuator assembly) is normal.

    • The pre-collision city sensor receives a stop light relay circuit malfunction signal from the skid control ECU (brake actuator assembly) for 1 second or more.

  • Lighting system

  • Vehicle stability control system

  • Skid control ECU (Brake actuator assembly)

  • Stop light relay (Stop light switch assembly)

  • Wire harness or connector

WIRING DIAGRAM

A002P8NE02

CAUTION / NOTICE / HINT

Note


  • When this DTC is output, a malfunction in the lighting system is suspected. Check if the lighting system is functioning normally Click here.

  • Inspect the fuses for circuits related to this system before performing the following procedure.

  • When replacing the pre-collision city sensor, replace it with a new one and be sure to initialize the settings. If a pre-collision city sensor which was installed to another vehicle is used, the information stored in the pre-collision city sensor will not match the information from the vehicle and, as a result, a DTC may be stored.

  • If the pre-collision city sensor has been replaced, or the windshield glass has been replaced or removed/installed, be sure to perform Pre-collision City Sensor Learning Click here.

  • w/ Smart Entry and Start System:

    When the start function does not operate, check the entry and start system (for start function) Click here.

PROCEDURE


  1. 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
      The stop lights illuminate when the brake pedal is depressed. The stop lights turn off when the brake pedal is released.

    NG

    GO TO LIGHTING SYSTEM Click here

    OK

  2. INSPECT STOP LIGHT SWITCH ASSEMBLY


    1. Inspect the stop light switch assembly Click here.

      OK
      The stop light switch assembly is normal.

    NG

    REPLACE STOP LIGHT SWITCH ASSEMBLY Click here

    OK

  3. CHECK FOR DTCs (VEHICLE STABILITY CONTROL SYSTEM)


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Enter the following menus: Chassis / ABS/VSC/TRAC / Trouble Codes.

    5. Check for DTCs Click here.

      Result
      Result Proceed to
      Vehicle stability control system DTCs are not output A
      Vehicle stability control system DTCs are output B

    B

    GO TO VEHICLE STABILITY CONTROL SYSTEM (DIAGNOSTIC TROUBLE CODE CHART) Click here

    A

  4. CHECK HARNESS AND CONNECTOR (STPO TERMINAL VOLTAGE)


    1. Turn the ignition switch off.

    2. A002PYFE02
      Text in Illustration
      *A for CVT
      *B except CVT
      *a

      Front view of wire harness connector

      (to Skid Control ECU (Brake Actuator Assembly))

      Disconnect the A78*1 or A79*2 skid control ECU (brake actuator assembly) connector.


      • *1: for CVT

      • *2: except CVT

    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      for CVT:
      Tester Connection Condition Specified Condition
      A78-3 (STPO) - Body ground Ignition switch ON 11 to 14 V
      except CVT:
      Tester Connection Condition Specified Condition
      A79-28 (STPO) - Body ground Ignition switch ON 11 to 14 V

    4. Connect the A78*1 or A79*2 skid control ECU (brake actuator assembly) connector.


      • *1: for CVT

      • *2: except CVT


    NG

    CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - SKID CONTROL ECU) Click here

    OK

  5. PERFORM ACTIVE TEST USING GTS (STOP LIGHT RELAY OUTPUT)


    1. According to the display on the GTS, perform the Active Test Stop Light Relay Click here.

      Chassis > ABS/VSC/TRAC > Active Test
      Tester Display Test Part Control Range Diagnostic Note
      Stop Light Relay Stop light control relay Relay ON / OFF Stop lights come on.

    2. According to the display on the GTS, read the Data List item Stop Light Relay Output Click here.

      Chassis > ABS/VSC/TRAC > Data List
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Stop Light Relay Output Stop light control relay output/ ON or OFF

      ON: Relay output on

      OFF: Relay output off

      		 -

    3. Check that the Data List item Stop Light Relay Output changes between ON and OFF and the stop lights turn on and off according to the operation of the Active Test.

      Result
      Result Proceed to
      The Data List item Stop Light Relay Output does not change between ON and OFF and the stop lights do not turn ON and OFF according to the operation of the Active Test. A
      The Data List item Stop Light Relay Output changes between ON and OFF but the stop lights do not turn ON and OFF according to the operation of the Active Test. B

    NG

    CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - SKID CONTROL ECU) Click here

    OK

  6. INSPECT SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY)


    1. According to the display on the GTS, perform the Active Test Stop Light Relay Click here.

      Chassis > ABS/VSC/TRAC > Active Test
      Tester Display Test Part Control Range Diagnostic Note
      Stop Light Relay Stop light control relay Relay ON / OFF Stop lights come on.

    2. Measure the voltage according to the value(s) in the table below.

      Tech Tips

      Do not disconnect the stop light switch assembly connector.

      Standard Voltage
      Tester Connection Condition Specified Condition
      A55-4 (ACC) - Body ground

      Ignition switch ON

      (Active test OFF)

      		 11 to 14 V

      Ignition switch ON

      (Active test ON)

      		 Below 1.5 V

    OK

    REPLACE STOP LIGHT SWITCH ASSEMBLY Click here

    NG

    REPLACE SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) Click here

  7. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - SKID CONTROL ECU)


    1. Turn the ignition switch off.

    2. Disconnect the A55 stop light switch assembly connector.

    3. Disconnect the A78*1 or A79*2 skid control ECU (brake actuator assembly) connector.


      • *1: for CVT

      • *2: except CVT

    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      for CVT:
      Tester Connection Condition Specified Condition
      A55-1 (OUT) - A78-22 (STP2) Always Below 1 Ω
      except CVT:
      Tester Connection Condition Specified Condition
      A55-1 (OUT) - A79-24 (STP2) Always Below 1 Ω

    5. Connect the A78*1 or A79*2 skid control ECU (brake actuator assembly) connector.


      • *1: for CVT

      • *2: except CVT

    6. Connect the A55 stop light switch assembly connector.


    OK

    REPLACE SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) Click here

    NG

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

  8. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - SKID CONTROL ECU)


    1. Turn the ignition switch off.

    2. Disconnect the A55 stop light switch assembly connector.

    3. Disconnect the A78*1 or A79*2 skid control ECU (brake actuator assembly) connector.


      • *1: for CVT

      • *2: except CVT

    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      for CVT:
      Tester Connection Condition Specified Condition
      A55-4 (ACC) - A78-3 (STPO) Always Below 1 Ω
      A55-4 (ACC) or A78-3 (STPO) - Body ground Always 10 kΩ or higher
      except CVT:
      Tester Connection Condition Specified Condition
      A55-4 (ACC) - A79-28 (STPO) Always Below 1 Ω
      A55-4 (ACC) or A79-28 (STPO) - Body ground Always 10 kΩ or higher

    5. Connect the A78*1 or A79*2 skid control ECU (brake actuator assembly) connector.


      • *1: for CVT

      • *2: except CVT

    6. Connect the A55 stop light switch assembly connector.


    OK

    REPLACE STOP LIGHT SWITCH ASSEMBLY Click here

    NG

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