PRE-CRASH SAFETY SYSTEM, Diagnostic DTC:C1A4B

DTC Code DTC Name
C1A4B Stop Light Relay Circuit

DESCRIPTION

The brake actuator assembly (skid control ECU) outputs a stop light signal to the stop light switch assembly. When the brake actuator assembly (skid control ECU) detects a malfunction relating to the stop light circuit, the pre-crash safety city sensor is notified via CAN communication, and C1A4B is output.

DTC Code DTC Detection Condition Trouble Area
C1A4B

  • Diagnosis condition:

    The ignition switch is ON and the pre-crash brake operates.


  • Malfunction condition:

    Either of the following conditions is met:

    - When the voltage at the IG1 terminal is between 11 V and 14 V and the stop light illumination output (STPO) is on, a signal has not been input to the STP2 terminal continuously for 0.3 seconds or more.

    - When the voltage at the IG1 terminal is between 11 V and 14 V and the stop light illumination output (STPO) is off, the input signals at the STP terminal and STP2 terminal differ continuously for 0.3 seconds or more.

  • Lighting system

  • Harness or connector

  • Stop light switch assembly

  • Pre-crash safety city sensor

WIRING DIAGRAM

A004RH1E02

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-crash safety city sensor, replace it with a new one. If an ECU which was installed to another vehicle is used, the information stored in the pre-crash safety city sensor will not match the information from the vehicle and, as a result, a DTC may be output.

  • When the pre-crash safety city sensor is replaced with a new one, camera beam axis learning must be performed. When replacing the pre-crash safety city sensor with a new one, or performing removal, installation or replacement of the windshield glass, always perform "Recognition Camera/ Target Position Memory" and "Beam Axis Learning".

    Perform adjustment with either "ONE TIME RECOGNITION" or "SEQUENTIAL RECOGNITION".


  • First check the CAN communication system by following How to Proceed with Troubleshooting. After checking that there are no malfunctions in the CAN communication system, proceed to troubleshooting Click here.

PROCEDURE


  1. CHECK STOP LIGHT OPERATION


    1. Check that the stop lights illuminate when the brake pedal is depressed and turn 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. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BATTERY AND BODY GROUND)


    1. A004U0FE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

      Disconnect the stop light switch assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A67-7 (B) - Body ground Always 11 to 14 V
      A67-6 (B) - Body ground Ignition switch ON 11 to 14 V

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A67-2 (GND) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK STOP LIGHT SWITCH ASSEMBLY


    1. A004U9UE01
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Brake Actuator Assembly [Skid Control ECU])

      Disconnect the brake actuator assembly (skid control ECU) connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A84-24 (STP2) - Body ground Brake pedal depressed 11 to 14 V
      A84-24 (STP2) - Body ground Brake pedal released Below 1.5 V

    NG

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

    OK

  4. PERFORM ACTIVE TEST USING GTS


    1. Enter the following menus: Chassis / ABS/VSC/TRC / Active Test.

    2. Perform "Active Test" according to the display on GTS.

      ABS/VSC/TRC
      Tester Display Test Part Control Range Diagnostic Note
      Stop Light Relay Switches stop light on/off ON/OFF Possible at vehicle speed of 0 km/h (0 mph)

    3. Enter the following menus: Chassis / ABS/VSC/TRC / Data List.

    4. Check the stop light switch assembly operation using the Data List and stop light operation by performing an Active Test.

      ABS/VSC/TRC
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Stop Light Relay Output Stop light switch assembly output / ON or OFF

      ON: Stop light switch assembly output on (Stop light on)

      OFF: Stop light switch assembly output off (Stop light off)

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

    B

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

    A

  5. CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY [SKID CONTROL ECU] - STOP LIGHT SWITCH ASSEMBLY)


    1. Disconnect the A84 brake actuator assembly (skid control ECU) connector.

    2. Disconnect the A67 stop light switch assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A84-28 (STPO) - A67-4 (ACC) Always Below 1 Ω
      A84-28 (STPO) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY [SKID CONTROL ECU] - STOP LIGHT SWITCH ASSEMBLY)


    • *: w/ Entry and Start System


    1. Disconnect the A84 brake actuator assembly (skid control ECU) connector.

    2. Disconnect the A67 stop light switch assembly connector.

    3. Disconnect the D113 power management control ECU connector.*

    4. Disconnect the A83 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A84-6 (STP) - A67-3 (L) Always Below 1 Ω
      A84-6 (STP) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  7. CHECK STOP LIGHT SWITCH ASSEMBLY


    1. A004T8RE01
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Brake Actuator Assembly [Skid Control ECU])

      Disconnect the brake actuator assembly (skid control ECU) connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A84-6 (STP) - Body ground Brake pedal depressed 11 to 14 V
      A84-6 (STP) - Body ground Brake pedal released Below 1.5 V

    NG

    REPLACE STOP LIGHT SWITCH ASSEMBLY Click here

    OK

  8. CHECK FOR DTCs


    1. Clear the DTCs Click here.

    2. Make sure that the DTC detection conditions are met.

      Tech Tips

      If the detection conditions are not met, the system cannot detect the malfunction.

    3. Using the GTS, perform the Active Test "Stop Light Relay" with the ignition switch ON Click here.

    4. Check for DTCs Click here.

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

    A

    USE SIMULATION METHOD TO CHECK Click here

    B

    REPLACE PRE-CRASH SAFETY CITY SENSOR Click here

  9. CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY [SKID CONTROL ECU] - STOP LIGHT SWITCH ASSEMBLY)


    1. Disconnect the A84 brake actuator assembly (skid control ECU) connector.

    2. Disconnect the A67 stop light switch assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A84-24 (STP2) - A67-1 (OUT) Always Below 1 Ω

    OK

    REPLACE STOP LIGHT SWITCH ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR