PRE-CRASH SAFETY SYSTEM, Diagnostic DTC:C1A4B

DTC Code DTC Name
C1A4B Stop Light Relay Circuit

DESCRIPTION

The brake actuator assembly (skid control ECU) sends a stop light operation request signal to the engine room junction block assembly (stop light relay). If the brake actuator assembly (skid control ECU) detects a malfunction in the stop light relay circuit, the driving support ECU assembly stores DTC C1A4B.

DTC No. DTC Detection Condition Trouble Area
C1A4B

Diagnosis condition:.

When the engine switch is on (IG) and the pre-crash brake control is operating, either of the following conditions is met:

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

  • Wire harness or connector

  • Brake actuator assembly (skid control ECU)

  • Engine room junction block assembly (stop light relay)

WIRING DIAGRAM

A01W06VE08

CAUTION / NOTICE / HINT

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.

  • 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. INSPECT ENGINE ROOM JUNCTION BLOCK ASSEMBLY


    1. Turn the engine switch off.

    2. Check the engine room junction block assembly Click here.

      OK
      The engine room junction block assembly is normal.

    NG

    INSPECT ENGINE ROOM JUNCTION BLOCK ASSEMBLY (RESULT OF SIGNAL READING CHECK) Click here

    OK

  2. CHECK HARNESS AND CONNECTOR (STPO TERMINAL VOLTAGE)


    1. Turn the engine switch off.

    2. A01W548E02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Brake Actuator Assembly (Skid Control ECU))

      Disconnect the A69 brake actuator assembly (skid control ECU) connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A69-26 (STPO) - Body ground Always 11 to 14 V

    NG

    CHECK HARNESS AND CONNECTOR (ENGINE ROOM JUNCTION BLOCK - BRAKE ACTUATOR ASSEMBLY) Click here

    OK

  3. PERFORM ACTIVE TEST USING GTS (STOP LIGHT 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 Switches stop light on/off ON/OFF Test possible at vehicle speed of 0 km/h (0 mph)

    2. Perform the Active Test of the engine room junction block assembly (stop light 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

      STPO terminal output condition/

      ON or OFF

      ON: Output

      OFF: Not output

      		 -

    4. Check for engine room junction block assembly (stop light 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 abnormal. A
      Data List content is normal but stop lights do not turn on or off. B

    B

    CHECK HARNESS AND CONNECTOR (ENGINE ROOM JUNCTION BLOCK - BRAKE ACTUATOR ASSEMBLY) Click here

    A

  4. INSPECT BRAKE ACTUATOR ASSEMBLY


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

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

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

      Tech Tips

      Do not disconnect the engine room junction block assembly connector.

      Standard Voltage
      Tester Connection Condition Specified Condition
      1G-3 (ACC) - Body ground

      Engine switch on (IG)

      (Active test is OFF)

      		 11 to 14 V
      1G-3 (ACC) - Body ground

      Engine switch on (IG)

      (Active test is ON)

      		 Below 1.5 V

    OK

    REPLACE ENGINE ROOM JUNCTION BLOCK ASSEMBLY (STOP LIGHT RELAY) Click here

    NG

    REPLACE BRAKE ACTUATOR ASSEMBLY Click here

  5. CHECK HARNESS AND CONNECTOR (ENGINE ROOM JUNCTION BLOCK - BRAKE ACTUATOR ASSEMBLY)


    1. Turn the engine switch off.

    2. Remove the engine room junction block assembly from the engine room relay block and junction block assembly

    3. Disconnect the A69 brake actuator assembly (skid control ECU) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1F-11 (STOP) - A69-5 (STP2) Always Below 1 Ω

    OK

    REPLACE BRAKE ACTUATOR ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  6. CHECK HARNESS AND CONNECTOR (ENGINE ROOM JUNCTION BLOCK - BRAKE ACTUATOR ASSEMBLY)


    1. Turn the engine switch off.

    2. Remove the engine room junction block assembly from the engine room relay block and junction block assembly

    3. Disconnect the A69 brake actuator assembly (skid control ECU) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1G-3 (ACC) - A69-26 (STPO) Always Below 1 Ω
      1G-3 (ACC) or A69-26 (STPO) - Body ground Always 10 kΩ or higher

    OK

    REPLACE ENGINE ROOM JUNCTION BLOCK ASSEMBLY (STOP LIGHT RELAY) Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR