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 No. 2 integration relay and the No. 2 integration relay illuminates the stop lights.

DTC Code DTC Detection Condition Trouble Area
C1A4B When the skid control ECU assembly detects a problem with the stop light control relay, a wire harness or a connector, the skid control ECU assembly sends a malfunction flag to the driving support ECU via CAN communication. When the driving support ECU receives the malfunction flag, DTC C1A48 is stored.

  • Lighting system

  • No. 2 integration relay

  • Skid control ECU assembly

  • Driving support ECU

  • Harness or connector

WIRING DIAGRAM

Refer to the wiring diagram for DTC C1380/64 Click here.

INSPECTION PROCEDURE

Note


  • When replacing the skid control ECU assembly, perform initialization and calibration of the linear solenoid valve Click here.

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

Tech Tips

When C1249/49 is output together with C1380/64, inspect and repair the trouble areas indicated by C1249/49 first 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 SWITCH)


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Select the Data List on the GTS Click here.

      ABS/VSC/TRC
      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

      		 -

    4. 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 (NO. 2 INTEGRATION RELAY)


    1. Select the Active Test on the GTS Click here.

      ABS/VSC/TRC
      Tester Display Test Part Control Range Diagnostic Note
      Stop Light Relay No. 2 integration relay Relay ON / OFF Stop lights come on
      EBS Relay

      No. 2 integration relay

      (Emergency brake signal)

      		 Relay ON / OFF No change*

      • *: w/o Emergency Brake Signal

    2. Perform the Active Test of the No. 2 integration relay using the GTS.

    3. Select the Data List on the GTS Click here.

      ABS/VSC/TRC
      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

      		 -
      EBS Relay No. 2 integration relay (Emergency brake signal) / ON or OFF

      OFF: Always*1

      ON: Relay on*2

      OFF: Relay off*2

      		 -

      • *1: w/o Emergency Brake Signal

      • *2: w/ Emergency Brake Signal

    4. Check for No. 2 integration relay operation using the Data List and stop light operation by performing an Active Test.

      Result
      Result Proceed to
      Data List content and stop light operation are normal A
      Data List content is normal but stop lights do not turn on or off B

    B

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

    A

  4. CHECK HARNESS AND CONNECTOR (STP2 TERMINAL)


    1. A01FR51E14
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Skid Control ECU Assembly)

      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. Disconnect the skid control ECU assembly connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A14-24 (STP2) - Body ground Stop light switch on (Brake pedal depressed) 8 to 14 V
      A14-24 (STP2) - Body ground Stop light switch off (Brake pedal released) Below 1.5 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (STP2 CIRCUIT)

    OK

  5. RECONFIRM DTC


    1. Reconnect the skid control ECU assembly connector.

    2. Clear the DTCs Click here.

    3. Turn the power switch on (Ready).

    4. Perform a road test.

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

      Result
      Result Proceed to
      DTC C1380/64 is not output A
      DTC C1380/64 is output B

    B

    REPLACE SKID CONTROL ECU ASSEMBLY Click here

    A

    CHECK FOR INTERMITTENT PROBLEMS Click here

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


    1. A01FRJYE02
      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

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


    1. A01FSUZE24
      Text in Illustration
      *a

      Front view of wire harness connector

      (to No. 2 Integration Relay)

      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

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


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

    2. Disconnect the A14 skid control ECU assembly connector.

    3. 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

  9. REPLACE NO. 2 INTEGRATION RELAY


    1. Reconnect the No. 2 integration relay connector.

    2. A01FR51E16
      Text in Illustration
      *A w/ Emergency Brake Signal
      *a

      Front view of wire harness connector

      (to Skid Control ECU Assembly)

      Disconnect the A16 skid control ECU assembly connector.

    3. Connect the terminals of the A16 connector of the skid control ECU assembly and check the stop light operating condition.

      Note

      Make sure to connect the terminals of the connector to the correct locations as not doing so may damage the connector.

      Standard
      w/o Emergency Brake Signal
      Condition Standard
      Stop Light Switch Assembly ON/OFF Condition A16-31 (STPO) - A16- 1 (GND4) Condition Stop Light Operation Condition

      Off

      (Brake pedal released)

      		 Disconnecting Not illuminated
      Connecting Illuminated

      On

      (Brake pedal depressed)

      		 Disconnecting Illuminated
      Connecting Illuminated
      w/ Emergency Brake Signal
      Condition Standard
      Stop Light Switch Assembly ON/OFF Condition A16-31 (STPO) - A16- 1 (GND4) Condition A16-2 (EXO) - A16- 1 (GND4) Condition Stop Light Operation Condition

      Off

      (Brake pedal released)

      		 Disconnecting Disconnecting Not illuminated
      Connecting Not illuminated
      Connecting Disconnecting Illuminated
      Connecting Illuminated

      On

      (Brake pedal depressed)

      		 Disconnecting Disconnecting Illuminated
      Connecting Not illuminated
      Connecting Disconnecting Illuminated
      Connecting Illuminated

    NG

    REPLACE NO. 2 INTEGRATION RELAY Click here

    OK

    REPLACE SKID CONTROL ECU ASSEMBLY Click here

  10. CHECK HARNESS AND CONNECTOR (STP TERMINAL)


    1. A01FR51E13
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Skid Control ECU Assembly)

      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. Disconnect the skid control ECU assembly connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A16-25 (STP) - Body ground Stop light switch on (Brake pedal depressed) 11 to 14 V
      A16-25 (STP) - Body ground Stop light switch off (Brake pedal released) Below 1.5 V
      Result
      Result Proceed to
      NG A
      OK (for LHD) B
      OK (for RHD) C

    B

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

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    A

    REPLACE SKID CONTROL ECU ASSEMBLY Click here

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


    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. Disconnect the A16 skid control ECU assembly connector.

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

    5. 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
      1A-18 (ESS) - A16-2 (EXO)* Always Below 1 Ω
      1A-18 (ESS) - Body ground* Always 10 kΩ or higher

      • *: w/ Emergency Brake Signal


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  12. INSPECT NO. 2 INTEGRATION RELAY


    1. A01FR51E16
      Text in Illustration
      *A w/ Emergency Brake Signal
      *a

      Front view of wire harness connector

      (to Skid Control ECU Assembly)

      Reconnect the No. 2 integration relay connector.

    2. Connect the terminals of the A16 connector of the skid control ECU assembly and check the stop light operating condition.

      Note

      Make sure to connect the terminals of the connector to the correct locations as not doing so may damage the connector.

      Standard
      w/o Emergency Brake Signal
      Condition Standard
      Stop Light Switch Assembly ON/OFF Condition A16-31 (STPO) - A16- 1 (GND4) Condition Stop Light Operation Condition

      Off

      (Brake pedal released)

      		 Disconnecting Not illuminated
      Connecting Illuminated

      On

      (Brake pedal depressed)

      		 Disconnecting Illuminated
      Connecting Illuminated
      w/ Emergency Brake Signal
      Condition Standard
      Stop Light Switch Assembly ON/OFF Condition A16-31 (STPO) - A16- 1 (GND4) Condition A16-2 (EXO) - A16- 1 (GND4) Condition Stop Light Operation Condition

      Off

      (Brake pedal released)

      		 Disconnecting Disconnecting Not illuminated
      Connecting Not illuminated
      Connecting Disconnecting Illuminated
      Connecting Illuminated

      On

      (Brake pedal depressed)

      		 Disconnecting Disconnecting Illuminated
      Connecting Not illuminated
      Connecting Disconnecting Illuminated
      Connecting Illuminated

    NG

    REPLACE NO. 2 INTEGRATION RELAY Click here

    OK

    REPLACE SKID CONTROL ECU ASSEMBLY Click here

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


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

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1A-6 (STP2) - A16-25 (STP) Always Below 1 Ω
      1A-6 (STP2) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS AND CONNECTOR

    OK

  14. REPLACE NO. 2 INTEGRATION RELAY


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


    NEXT

  15. 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 WAS DEFECTIVE)