PRE-CRASH SAFETY SYSTEM, Diagnostic DTC:C1A4B

DTC Code DTC Name
C1A4B Stop Light Relay Circuit

DESCRIPTION

The skid control ECU assembly outputs a stop light operation signal to the stop light control relay. When the skid control ECU 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 When the power switch on (IG), the IG1 terminal voltage is between 11 and 14 V, there is no input signal to terminal STP2 of the skid control ECU assembly for 0.3 seconds or more when the stop light illumination output (STP0) of the skid control ECU assembly is ON, or the input signals to terminals STP and STP2 of the skid control ECU assembly are different for 0.3 seconds or more when the stop light illumination output (STP0) of the skid control ECU assembly is OFF.

  • Light system

  • Vehicle stability control system

  • Harness or connector

  • No. 2 integration relay

  • Driving support ECU

WIRING DIAGRAM

A01FQRKE01

INSPECTION PROCEDURE

Note


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

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

    GO TO LIGHTING SYSTEM Click here

    OK

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


    1. A01FRJYE03
      Text in Illustration
      *a

      Front view of wire harness connector

      (to No. 2 Integration Relay)

      Turn the power 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
      1B-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
      1A-22 (GNDA) - Body ground Always Below 1 Ω
      1B-10 (GNDB) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK HARNESS AND CONNECTOR (STP TERMINAL)


    1. Turn the power switch off.

    2. A01FR51E17
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Skid Control ECU Assembly)

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

    3. Disconnect the skid control ECU assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A16-25 (STP) - Body ground Brake pedal depressed 11 to 14 V
      Brake pedal released Below 1.5 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. Turn the power switch off.

    2. A01FSUZE24
      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
      1A-11 (STP0) - Body ground Brake pedal depressed 11 to 14 V
      Brake pedal released Below 1.5 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. Turn the power 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 - SKID CONTROL ECU ASSEMBLY) Click here

    A

  6. CHECK HARNESS AND CONNECTOR (NO. 2 INTEGRATION RELAY - SKID CONTROL ECU ASSEMBLY)


    1. Turn the power switch off.

    2. Disconnect the 1A No. 2 integration relay connector.

    3. Disconnect the A16 skid control ECU assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1A-7 (ACC) - A16-31 (STPO) Always Below 1 Ω
      1A-7 (ACC) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  7. CHECK HARNESS AND CONNECTOR (NO. 2 INTEGRATION RELAY - SKID CONTROL ECU ASSEMBLY)


    1. Turn the power switch off.

    2. Disconnect the 1A No. 2 integration relay connector.

    3. Disconnect the A14 skid control ECU assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1A-3 (STOP) - A14-24 (STP2) Always Below 1 Ω
      1A-3 (STOP) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  8. CHECK HARNESS AND CONNECTOR (STP2 TERMINAL)


    1. Turn the power switch off.

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

    3. A01FR51E14
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Skid Control ECU Assembly)

      Disconnect the skid control ECU assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A14-24 (STP2) - Body ground Brake pedal depressed 11 to 14 V
      Brake pedal released Below 1.5 V

    NG

    REPLACE NO. 2 INTEGRATION RELAY Click here

    OK

  9. CHECK FOR DTC


    1. Turn the power switch off and wait for at least 2 minutes.

    2. Clear the DTCs Click here.

    3. 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 power switch on (IG).

    4. Check for DTCs Click here.

      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.

      OK
      DTC C1A4B is not output.

    NG

    REPLACE DRIVING SUPPORT ECU Click here

    OK

    END