AUTOMATIC TRANSMISSION SYSTEM, Diagnostic DTC:U0121

DTC Code DTC Name
U0121 Lost Communication with Anti-Lock Brake System (ABS) Control Module

DESCRIPTION

The TCM receives signals sent from the skid control ECU via CAN communication. When DTCs indicating a CAN communication system malfunction are output, repair the CAN communication system before repairing each corresponding ECU or sensor.

DTC No.

DTC Detection Condition


  1. Diagnosis Condition

  2. Malfunction Status

  3. Malfunction Time

  4. Other

 Trouble Area
P0121

  1. Battery voltage is 9.5 V or higher

  2. No communication between the skid control ECU and TCM

  3. 1.25 seconds

  4. 1-trip detection logic

  • CAN communication system

  • Skid control ECU

CAUTION / NOTICE / HINT

Note

Perform registration and/or initialization when parts related to the automatic transmission are replaced Click here.

Tech Tips

After performing repair, clear the DTCs and perform the following procedure to check that DTCs are not output.


  1. Check the battery voltage is 9.5 V or higher.

  2. Turn the engine switch on (IG).

  3. Check for DTCs again Click here.

PROCEDURE


  1. CHECK DTC OUTPUT


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / ECT / Trouble Codes.

    5. Read the DTCs using the GTS.

      Result
      Result Proceed to
      DTC U0100 is output A
      DTC U0100 is not output (for LHD) B
      DTC U0100 is not output (for RHD) C

    A

    GO TO DTC P0100 FLOWCHART Click here

    B

    GO TO CAN COMMUNICATION SYSTEM Click here

    C

    GO TO CAN COMMUNICATION SYSTEM Click here