DYNAMIC RADAR CRUISE CONTROL SYSTEM, Diagnostic DTC:C1A4B

DTC Code DTC Name
C1A4B Stop Light Relay Circuit

DESCRIPTION

The brake actuator assembly outputs a stop light operation signal to the stop light control relay. When the brake actuator assembly detects a malfunction in the circuit related to the stop light, it informs the driving support ECU via CAN communication and stores DTC C1A4B.

DTC Code DTC Detection Condition Trouble Area
C1A4B

  • Pre-crash safety system:


    • The engine switch is on (IG).


  • Radar cruise control system:


    • The vehicle is being driven at a speed of approximately 50 km/h (31 mph) or more and the ACC main switch is on.

When the IG1 terminal voltage is between 11 and 14 V, there is no input signal to terminal STP2 of the brake actuator assembly for 5 seconds or more when the stop light illumination output (STP0) of the brake actuator assembly is on, or the input signals to terminals STP and STP2 of the brake actuator assembly are different for 5 seconds or more when the stop light illumination output (STP0) of the brake actuator assembly is off.

  • Lighting system

  • No. 2 integration relay

  • Brake actuator assembly

  • Driving support ECU

  • Harness or connector

WIRING DIAGRAM

A01FI5IE03

INSPECTION PROCEDURE

Note


  • When replacing the brake actuator assembly, perform zero point calibration and store system information Click here.

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

Tech Tips

When DTC C1425 and/or C1426 is output together with DTC C1380, inspect and repair the trouble areas indicated by DTC C1425 and/or C1426 first Click here, or 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
      Condition Illumination Condition
      Brake pedal depressed ON
      Brake pedal released OFF

    NG

    CHECK HARNESS AND CONNECTOR (NO. 2 INTEGRATION RELAY POWER SOURCE TERMINAL) Click here

    OK

  2. READ VALUE USING GTS (STOP LIGHT SW)


    1. Turn the engine switch off.

    2. Connect the GTS to the DLC3.

    3. Start the engine.

    4. Turn the GTS on.

    5. Enter the following menus: Chassis / ABS/VSC/TRAC / Data List.

      ABS/VSC/TRAC
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Stop Light SW Stop light switch / ON or OFF

      ON: Brake pedal depressed

      OFF: Brake pedal released

      		 -

    6. Check that the stop light switch condition observed on the GTS changes according to brake pedal operation.

      OK
      The GTS displays ON or OFF according to brake pedal operation.

    NG

    CHECK HARNESS AND CONNECTOR (STP TERMINAL) Click here

    OK

  3. PERFORM ACTIVE TEST USING GTS (STOP LIGHT RELAY)


    1. Turn the engine switch off.

    2. Connect the GTS to the DLC3.

    3. Start the engine.

    4. Turn the GTS on.

    5. Enter the following menus: Chassis / ABS/VSC/TRAC / Active Test.

      ABS/VSC/TRAC
      Tester Display Test Part Control Range Diagnostic Note
      Stop Light Relay No. 2 integration relay ON / OFF Observe the stop light (the stop lights do not come on for 2 to 5 seconds).

    6. While performing the Active Test, check the illumination condition of the stop lights and "Stop Light Relay Output" in the Data List.

      ABS/VSC/TRAC
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Stop Light Relay Output No. 2 integration relay output / ON or OFF

      ON: Relay output ON

      OFF: Relay output OFF

      		 -
      Result
      Result Proceed to
      When Active Test performed, Data List item changes between ON and OFF, but stop lights do not turn on A
      When Active Test performed, Data List item changes between ON and OFF and stop lights turn on and off B

    B

    CHECK HARNESS AND CONNECTOR (NO. 2 INTEGRATION RELAY - BRAKE ACTUATOR ASSEMBLY) Click here

    A

  4. 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.

    3. A01FH1RE03
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Brake Actuator Assembly)

      Disconnect the brake actuator assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A13-22 (STP2) - Body ground Brake pedal depressed 8 to 14 V
      Brake pedal released Below 1.5 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. RECONFIRM DTC


    1. Reconnect the brake actuator assembly connector.

    2. Clear the DTCs Click here.

    3. Turn the engine switch off.

    4. Start the engine.

    5. Check if the same DTC is recorded Click here.

      Result
      Result Proceed to
      DTC (C1380) is not output A
      DTC (C1380) is output B

    B

    REPLACE BRAKE ACTUATOR ASSEMBLY Click here

    A

    CHECK FOR INTERMITTENT PROBLEMS Click here

  6. CHECK HARNESS AND CONNECTOR (NO. 2 INTEGRATION RELAY POWER SOURCE TERMINAL)


    1. A01FIIME01
      Text in Illustration
      *a

      Front view of wire harness connector

      (to No. 2 Integration Relay)

      Turn the engine switch off.

    2. Disconnect the No. 2 integration relay connectors.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      2B-7 (BATT) - Body ground Always 11 to 14 V

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      2A-22 (GNDA) - Body ground Always Below 1 Ω
      2B-10 (GNDB) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  7. CHECK HARNESS AND CONNECTOR (BATTERY - NO. 2 INTEGRATION RELAY)


    1. Turn the engine switch off.

    2. A01FIPDE21
      Text in Illustration
      *a

      Front view of wire harness connector

      (to No. 2 Integration Relay)

      Disconnect the No. 2 integration relay connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      2A-11 (STPO) - Body ground Brake pedal depressed 8 to 14 V
      Brake pedal released Below 1.5 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  8. CHECK HARNESS AND CONNECTOR (NO. 2 INTEGRATION RELAY - BRAKE ACTUATOR ASSEMBLY)


    1. Turn the engine switch off.

    2. Disconnect the 2A No. 2 integration relay connector.

    3. Disconnect the A13 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
      2A-3 (STOP) - A13-22 (STP2) Always Below 1 Ω
      2A-3 (STOP) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE NO. 2 INTEGRATION RELAY Click here

  9. CHECK HARNESS AND CONNECTOR (STP TERMINAL)


    1. Turn the engine switch off.

    2. A01FH1RE04
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Brake Actuator Assembly)

      Make sure that there is no looseness at the locking part and the connecting part of the connector.

    3. Disconnect the brake actuator assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A13-2 (STP) - Body ground Brake pedal depressed 8 to 14 V
      Brake pedal released Below 1.5 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  10. CHECK HARNESS AND CONNECTOR (NO. 2 INTEGRATION RELAY - BRAKE ACTUATOR ASSEMBLY)


    1. Turn the engine switch off.

    2. Disconnect the 2A No. 2 integration relay connector.

    3. Disconnect the A13 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
      2A-7 (ACC) - A13-31 (STPO) Always Below 1 Ω
      2A-7 (ACC) - Body ground Always 10 kΩ or higher
      2A-18 (ESS) - A13-8 (EXO)* Always Below 1 Ω
      2A-18 (ESS) - Body ground* Always 10 kΩ or higher

      • *: w/ Emergency Brake Signal


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  11. CHECK HARNESS AND CONNECTOR (NO. 2 INTEGRATION RELAY - BRAKE ACTUATOR ASSEMBLY)


    1. Turn the engine switch off.

    2. Disconnect the 2A No. 2 integration relay connector.

    3. Disconnect the A13 brake actuator assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      2A-3 (STOP) - A13-22 (STP2) Always Below 1 Ω
      2A-3 (STOP) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  12. REPLACE NO. 2 INTEGRATION RELAY


    1. Replace the No. 2 integration relay with a new or normally functioning one Click here.


    NEXT

  13. CHECK FOR DTC


    1. Clear the DTCs Click here.

    2. Check for DTCs Click here.

      OK
      DTC C1A4B is not output.

      Note

      When replacing the driving support ECU, always replace it with a new one and be sure to perform initialization Click here. If an ECU which was installed to another vehicle is used, the information stored in the ECU will not match the information from the vehicle, and as a result, a DTC may be stored.


    NG

    REPLACE DRIVING SUPPORT ECU Click here

    OK

    END (NO. 2 INTEGRATION RELAY IS DEFECTIVE)