Toyota Corolla Cross Owners & Service Manuals

Toyota Corolla Cross: Lost Communication with Brake System Control Module Missing Message (U012987)

Toyota Corolla Cross (2022-2024) Service Manual / Engine & Hybrid System / M20a-fxs (engine Control) / Sfi System / Lost Communication with Brake System Control Module Missing Message (U012987)

MONITOR DESCRIPTION

The ECM and skid control ECU send and receive signals via CAN communication.

If a communication error occurs between the ECM and skid control ECU, the ECM illuminates the MIL and stores this DTC.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Note

U012987

Lost Communication with Brake System Control Module Missing Message

All of the following conditions are met for 4.98 seconds or more (1 trip detection logic):

  • Ignition switch ON
  • Auxiliary battery voltage 10 V or higher
  • No communication between ECM and skid control ECU
  • CAN communication system
  • Skid control ECU
  • ECM

Comes on

  • SAE Code: U0129
  • DTC for Mexico Models: Does not apply

MONITOR STRATEGY

Related DTCs

U0129: Lost communication with brake system control module

Required Sensors/Components (Main)

ECM

Required Sensors/Components (Related)

-

Frequency of Operation

Continuous

Duration

4.98 seconds

MIL Operation

Immediate

Sequence of Operation

None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever the following DTCs are not stored

None

Both of the following conditions are met

-

Auxiliary battery voltage

10 V or higher

Ignition switch

ON

TYPICAL MALFUNCTION THRESHOLDS

Communication signal

Lost communication with brake system control module

CONFIRMATION DRIVING PATTERN

HINT:

  • After repair has been completed, clear the DTC and then check that the vehicle has returned to normal by performing the following All Readiness check procedure.

    Click here

  • When clearing the permanent DTCs, refer to the "CLEAR PERMANENT DTC" procedure.

    Click here

  1. Connect the GTS to the DLC3.
  2. Turn the ignition switch to ON.
  3. Turn the GTS on.
  4. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
  5. Turn the ignition switch off and wait for at least 30 seconds.
  6. Turn the ignition switch to ON [A].
  7. Turn the GTS on.
  8. Wait 5 seconds or more.
  9. Enter the following menus: Powertrain / Engine / Trouble Codes [B].
  10. Read the pending DTCs.

    HINT:

    • If a pending DTC is output, the system is malfunctioning.
    • If a pending DTC is not output, perform the following procedure.
  11. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
  12. Input the DTC: U012987.
  13. Check the DTC judgment result.

    GTS Display

    Description

    NORMAL

    • DTC judgment completed
    • System normal

    ABNORMAL

    • DTC judgment completed
    • System abnormal

    INCOMPLETE

    • DTC judgment not completed
    • Perform driving pattern after confirming DTC enabling conditions

    HINT:

    • If the judgment result shows NORMAL, the system is normal.
    • If the judgment result shows ABNORMAL, the system is malfunctioning.
    • [A] to [B]: Normal judgment procedure.

      The normal judgment procedure is used to complete DTC judgment and also used when clearing permanent DTCs.

    • When clearing the permanent DTCs, do not disconnect the cable from the auxiliary battery terminal or attempt to clear the DTCs during this procedure, as doing so will clear the universal trip and normal judgment histories.

CAUTION / NOTICE / HINT

NOTICE:

  • Vehicle Control History may be stored in the hybrid vehicle control ECU assembly if the engine is malfunctioning. Certain vehicle condition information is recorded when Vehicle Control History is stored. Reading the vehicle conditions recorded in both the Freeze Frame Data and Vehicle Control History can be useful for troubleshooting.

    Click here

    (Select Powertrain in Health Check and then check the time stamp data.)

    Click here

  • If any "Engine Malfunction" Vehicle Control History item has been stored in the hybrid vehicle control ECU assembly, make sure to clear it. However, as all Vehicle Control History items are cleared simultaneously, if any Vehicle Control History items other than "Engine Malfunction" are stored, make sure to perform any troubleshooting for them before clearing Vehicle Control History.

    Click here

HINT:

Read freeze frame data using the GTS. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.

PROCEDURE

1.

GO TO CAN COMMUNICATION SYSTEM

Click here

NEXT

END

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