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PRE-COLLISION SYSTEM, Diagnostic DTC:C1A4B

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DTC Code DTC Name
C1A4B Stop Light Relay Circuit
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DESCRIPTION

The skid control ECU (brake actuator assembly) sends a stop light operation request signal to the stop light relay (stop light switch assembly). If the skid control ECU (brake actuator assembly) detects a malfunction in the stop light 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 While the ignition switch is ON, the millimeter wave radar sensor assembly receives a stop light relay circuit malfunction signal from the skid control ECU (brake actuator assembly) for 1 second or more.

  • Vehicle stability control system

  • Millimeter wave radar sensor assembly
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CAUTION / NOTICE / HINT

Note:

  • When replacing the millimeter wave radar sensor assembly, always replace it with a new one. If a millimeter wave radar sensor assembly which was installed to another vehicle is used, the information stored in the millimeter wave radar sensor assembly will not match the information from the vehicle. As a result, a DTC may be stored.

  • If the millimeter wave radar sensor assembly has been replaced, be sure to perform millimeter wave radar sensor assembly adjustment.

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

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PROCEDURE


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    CHECK FOR DTCs (VEHICLE STABILITY CONTROL SYSTEM)

    Tip:

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


    1. Check for DTCs.


      1. 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

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    CHECK FOR DTCs (PRE-COLLISION SYSTEM)


    1. Clear the DTCs.


      1. Body Electrical > Pre-Collision 2 > Clear DTCs


    2. Perform the following procedure.

      Tip:

      If the following procedure is not performed, the previously output DTC cannot be detected.


      1. Turn the ignition switch to ON and wait 1 second or more.

    3. Check for DTCs.


      1. Body Electrical > Pre-Collision 2 > Trouble Codes


      Result
      Result Proceed to
      DTC C1A4B is not output A
      DTC C1A4B is output B

    • A

      USE SIMULATION METHOD TO CHECKClick here

    • B

      REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLYClick here