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 relay. 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 DTC C1A4B is stored.

DTC No. Detection Item DTC Detection Condition Trouble Area
C1A4B Stop Light Relay Circuit

  • Diagnosis condition:

    3 seconds after the ignition switch turned to ON and pre-crash brake control is performed.

    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) signal 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) signal is off, the input signals at the STP terminal and STP2 terminal differ continuously for 0.3 seconds or more.

  • Lighting system

  • Vehicle stability control system

  • Harness or connector

  • STOP LP relay

  • Pre-crash safety city sensor

WIRING DIAGRAM

A0030GVE13

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 and be sure to initialize the settings. If a pre-crash safety city sensor 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 stored.

  • If the pre-crash safety city sensor has been replaced, or the windshield glass has been replaced or removed/installed, be sure to perform Recognition Camera/Target Position Memory and Recognition Camera Axis Adjust.

    Click here

  • 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 with troubleshooting.

    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.
      Result
      Proceed to
      OK
      NG

    NG

    GO TO LIGHTING SYSTEM Click here

    OK

  2. CHECK HARNESS AND CONNECTOR (STOP LP RELAY POWER SOURCE)


    1. A0030XJC08
      *a Engine Room Relay Block and Junction Block Assembly (Relay Holder)

      Remove the STOP LP relay from the engine room relay block and junction block assembly.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      Relay holder terminal 5 - Body ground Ignition switch off 11 to 14 V
      Relay holder terminal 2 - Body ground Ignition switch ON 11 to 14 V

    3. Reinstall the STOP LP relay to the engine room relay block and junction block assembly.

      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK HARNESS AND CONNECTOR (STP2 TERMINAL)


    1. A0030K4C01
      *a

      Front view of wire harness connector

      (to Brake Actuator Assembly (Skid Control ECU))

      Disconnect the A97 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
      A97-22 (STP2) - Body ground Brake pedal depressed 11 to 14 V
      A97-22 (STP2) - Body ground Brake pedal released Below 1.5 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. CHECK HARNESS AND CONNECTOR (STOP LIGHT VOLTAGE)


    1. A0030XJC09
      *a Engine Room Relay Block and Junction Block Assembly (Relay Holder)

      Remove the STOP LP relay from the engine room relay block and junction block assembly.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      Relay holder terminal 4 - Body ground

      Stop light switch assembly on

      (Brake pedal depressed)

      		 11 to 14 V
      Relay holder terminal 4 - Body ground

      Stop light switch assembly off

      (Brake pedal released)

      		 Below 2 V

    3. Reinstall the STOP LP relay to the engine room relay block and junction block assembly.

      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. 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 the GTS.

      Click here


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

      Chassis > ABS/VSC/TRC > Active Test
      Active Test Display
      Stop Light Relay
      Data List Display
      Stop Light Relay Output

    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.


      Chassis > ABS/VSC/TRC > Data List
      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Stop Light Relay Output STPO terminal output condition ON or OFF

      ON: Output

      OFF: Not output

      		 -
      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

    GO TO STEP 7 Click here

    A

  6. CHECK HARNESS AND CONNECTOR (STOP LP RELAY - BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU))


    1. A0030K4C02
      *a

      Front view of wire harness connector

      (to Brake Actuator Assembly (Skid Control ECU))

      Disconnect the A97 brake actuator assembly (skid control ECU) connector.

    2. A0030XJC09
      *a Engine Room Relay Block and Junction Block Assembly (Relay Holder)

      Remove the STOP LP relay from the engine room relay block and junction block assembly.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      Relay holder terminal 1 - A97-3 (STPO) Always Below 1 Ω
      Relay holder terminal 1 or A97-3 (STPO) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    4. Reinstall the STOP LP relay to the engine room relay block and junction block assembly.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  7. CHECK HARNESS AND CONNECTOR (STOP LP RELAY - BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU))


    1. A0030K4C03
      *a

      Front view of wire harness connector

      (to Brake Actuator Assembly (Skid Control ECU))

      Disconnect the A97 brake actuator assembly (skid control ECU) connector.

    2. A0030XJC09
      *a Engine Room Relay Block and Junction Block Assembly (Relay Holder)

      Remove the STOP LP relay from the engine room relay block and junction block assembly.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      Relay holder terminal 3 - A97-30 (STP) Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    4. Reinstall the STOP LP relay to the engine room relay block and junction block assembly.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  8. CHECK HARNESS AND CONNECTOR (STP TERMINAL)


    1. A0030K4C03
      *a

      Front view of wire harness connector

      (to Brake Actuator Assembly (Skid Control ECU))

      Disconnect the A97 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
      A97-30 (STP) - Body ground Brake pedal depressed 11 to 14 V
      A97-30 (STP) - Body ground Brake pedal released Below 1.5 V
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE STOP LP RELAY Click here

    OK

  9. CHECK FOR DTCS


    1. Clear the DTCs.

      Click here


      Chassis > PCS/LDA/RSA/LVN > Clear DTCs

    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.


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

        Click here

    3. Check for DTCs.

      Click here


      Chassis > PCS/LDA/RSA/LVN > Trouble Codes
      Result
      Result Proceed to
      DTC C1A4B is not output A
      DTC C1A4B is output B

    A

    END

    B

    REPLACE PRE-CRASH SAFETY CITY SENSOR Click here