ELECTRONICALLY CONTROLLED BRAKE SYSTEM, Diagnostic DTC:C1203

DTC Code DTC Name
C1203 ECM Communication Circuit Malfunction

DESCRIPTION

The circuit is used to send TRC and VSC control information from the skid control ECU (brake actuator assembly) to the ECM, and engine control information from the ECM to the skid control ECU (brake actuator assembly) through the CAN communication system.

DTC No. Detection Item DTC Detection Condition Trouble Area Note
C1203 ECM Communication Circuit Malfunction

Either of the following is detected:


  • Engine, drive source and destination information sent from the ECM does not match the information of the skid control ECU or there is no information in memory.

  • The DRS availability, VGRS type and active stabilizer suspension system coordinated control availability information of the VGRS ECU (front steering control ECU) does not match the information stored in the skid control ECU.

  • The VGRS setting availability information for the steering sensor does not match the information stored in the skid control ECU.

  • No system information stored in the skid control ECU.

  • Incorrect installation of the skid control ECU or ECM.

  • When the skid control ECU is malfunctioning.

  • Incorrect ECM installed, or ECM malfunction

  • Incorrect VGRS ECU (front steering control ECU) installed, or ECU malfunction

  • Incorrect steering sensor installed, or sensor malfunction

  • Skid control ECU (Brake actuator assembly)

 -
C1203 DTC Detection Conditions
Vehicle Condition
Pattern 1 Pattern 2 Pattern 3 Pattern 4 Pattern 5 Pattern 6
Diagnosis Condition - - - - - - -
Malfunction Status Engine, drive source and destination information sent from the ECM does not match the information of the skid control ECU or there is no information in memory. ○ - - - - -
The DRS availability, VGRS type and active stabilizer suspension system coordinated control availability information of the VGRS ECU (front steering control ECU) does not match the information stored in the skid control ECU. - ○ - - - -
The VGRS setting availability information for the steering sensor does not match the information stored in the skid control ECU. - - ○ - - -
No system information stored in the skid control ECU. - - - ○ - -
Incorrect installation of the skid control ECU or ECM - - - - ○ -
When the skid control ECU is malfunctioning. - - - - - ○
Detection Time - - - - - -
Number of Trips 1 trip 1 trip 1 trip 1 trip 1 trip 1 trip

Tech Tips

DTC will be output when conditions for either of the patterns in the table above are met.

CAUTION / NOTICE / HINT

Note

When replacing the skid control ECU (brake actuator assembly), perform zero point calibration and store system information.

Click here

PROCEDURE


  1. CHECK PART NUMBER (ECM)


    1. Check that the proper ECM is installed.

      OK
      Proper ECM is installed.

    2. Check if the ECM was replaced before the DTC was stored.

      OK
      ECM was not replaced
      Result
      Result Proceed to
      OK A
      NG (A proper ECM is not installed and/or the ECM was replaced.) B

    B

    REPLACE ECM Click here

    A

  2. CHECK PART NUMBER (VGRS ECU [FRONT STEERING CONTROL ECU])


    1. For vehicles with the VGRS system, check that the part number of the installed VGRS ECU (front steering control ECU) is correct. For vehicles without the VGRS system, make sure that a VGRS ECU (front steering control ECU) is not installed.

      OK
      The presence or absence of the VGRS ECU (front steering control ECU) appropriately matches the specifications of the vehicle.

    2. Check if the VGRS ECU (front steering control ECU) had been replaced before the DTC was stored.

      OK
      ECU had not been replaced.
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE FRONT STEERING CONTROL ECU Click here

    OK

  3. CHECK PART NUMBER (STEERING SENSOR)


    1. Check that the installed steering sensor matches the vehicle (vehicles equipped with VGRS or vehicles not equipped with VGRS)

      OK
      The steering sensor installation matches the vehicle specification.

    2. Check if the steering sensor had been replaced before the DTC was stored.

      OK
      Sensor had not been replaced.
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE STEERING SENSOR Click here

    OK

  4. CHECK BRAKE ACTUATOR ASSEMBLY


    1. Check that the proper brake actuator assembly is installed.

      OK
      Proper brake actuator assembly is installed.

    2. Check if the brake actuator assembly was replaced before the DTC was recorded.

      OK
      The brake actuator assembly was not replaced.
      Result
      Result Proceed to
      OK A
      NG (A proper brake actuator assembly is not installed.) B
      NG (The brake actuator assembly was replaced.) C

    B

    REPLACE BRAKE ACTUATOR ASSEMBLY for LHD: Click here
    REPLACE BRAKE ACTUATOR ASSEMBLY for RHD: Click here

    C

    PERFORM INITIALIZATION AND CALIBRATION Click here

    A

  5. RECONFIRM DTC


    1. Clear the DTC.

      Click here


      Chassis > ABS/VSC/TRC > Clear DTCs

    2. Check if the same DTC is recorded.

      Click here


      Chassis > ABS/VSC/TRC > Trouble Codes
      Result
      Result Proceed to
      DTC C1203 is not output. A
      DTC C1203 is output. B

    A

    USE SIMULATION METHOD TO CHECK Click here

    B

    REPLACE BRAKE ACTUATOR ASSEMBLY for LHD: Click here
    REPLACE BRAKE ACTUATOR ASSEMBLY for RHD: Click here

  6. PERFORM INITIALIZATION AND CALIBRATION


    1. Perform initialization and calibration.

      Click here

      Result
      Proceed to
      NEXT

    NEXT

  7. RECONFIRM DTC


    1. Clear the DTC.

      Click here


      Chassis > ABS/VSC/TRC > Clear DTCs

    2. Check if the same DTC is recorded.

      Click here


      Chassis > ABS/VSC/TRC > Trouble Codes
      Result
      Result Proceed to
      DTC C1203 is not output. A
      DTC C1203 is output. B

    A

    END

    B

    REPLACE BRAKE ACTUATOR ASSEMBLY for LHD: Click here
    REPLACE BRAKE ACTUATOR ASSEMBLY for RHD: Click here