PRE-COLLISION SYSTEM, Diagnostic DTC:C1A4B

DTC Code DTC Name
C1A4B Stop Light Relay Circuit

DESCRIPTION

The skid control ECU (brake actuator assembly) sends a stop light operation request signal to the stop light control relay (STOP/CDS FAN Relay). If the skid control ECU (brake actuator assembly) detects a malfunction in the stop light control relay (STOP/CDS FAN Relay) circuit, the millimeter wave radar sensor assembly stores DTC C1A4B.

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

Diagnosis condition:


  • Ignition switch to ON and battery voltage between 11 and 14 V

Malfunction condition:

Either of the following conditions is met:


  • When the stop light illumination output (STPO) signal is on, a signal has not been input to the STP terminal for 1 second or more continuously.

  • When the stop light illumination output (STPO) signal is off, signals input to the STP terminal and STP2 terminal of the skid control ECU (brake actuator assembly) differ for 1 second or more continuously.

  • Vehicle stability control system

  • Millimeter wave radar sensor assembly

  • Skid control ECU (Brake actuator assembly)

WIRING DIAGRAM

B0027ICE01

CAUTION / NOTICE / HINT

Note

The pre-collision system uses the CAN communication system. First, confirm that there are no malfunction in the CAN communication system. Refer to How to Proceed with Troubleshooting.

for LHD: Click here

for RHD: Click here

PROCEDURE


  1. CHECK FOR DTCs (VEHICLE STABILITY CONTROL SYSTEM)

    Tech Tips

    Pre-collision system DTC C1A4B may be stored due to a malfunction in the VSC system. Therefore, it is necessary to check for and troubleshoot VSC system DTCs first.


    1. Check for DTCs.

      Click here


      Chassis > ABS/VSC/TRC > Trouble Codes
      Result
      Result Proceed to
      Vehicle stability control system DTCs are not output A
      Vehicle stability control system DTCs are output B

    B

    GO TO VEHICLE STABILITY CONTROL SYSTEM Click here

    A

  2. CHECK FOR DTCs (PRE-COLLISION SYSTEM)


    1. Clear the DTCs.

      Click here


      Body Electrical > Pre-Collision 2 > 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.

    3. Check for DTCs.

      Click here


      Body Electrical > Pre-Collision 2 > Trouble Codes
      Result
      Result Proceed to
      DTC C1A4B is output A
      DTC C1A4B is not output B

    B

    USE SIMULATION METHOD TO CHECK Click here

    A

  3. REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY


    1. Replace the millimeter wave radar sensor assembly.

      Click here

    2. Adjust the millimeter wave radar sensor assembly.

      Click here

      Result
      Proceed to
      NEXT

    NEXT

  4. CHECK FOR DTCs (PRE-COLLISION SYSTEM)

    Tech Tips

    After performing the radar sensor beam axis adjustment, if the same DTC is output again after the DTC detection conditions are met, replace the millimeter wave radar sensor assembly.


    1. Clear the DTCs.

      Click here


      Body Electrical > Pre-Collision 2 > 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.

    3. Check for DTCs.

      Click here


      Body Electrical > Pre-Collision 2 > Trouble Codes
      Result
      Result Proceed to
      DTC C1A4B is not output A
      DTC C1A4B is output B

    A

    END (MILLIMETER WAVE RADAR SENSOR ASSEMBLY WAS DEFECTIVE)

    B

    REPLACE SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) Click here