Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Lost Communication with TCM Missing Message (U010187)

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Engine & Hybrid System / 2gr-fks (engine Control) / Sfi System / Lost Communication with TCM Missing Message (U010187)

MONITOR DESCRIPTION

The engine control unit and the transmission control unit are located inside the ECM. The engine control unit intercommunicates with the transmission control via CAN communication.

If there is a problem in this communication, the ECM store this DTC.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

Note

U010187

Lost Communication with TCM Missing Message

All of the following conditions are met for 1.25 seconds (1 trip detection logic):

  • Engine switch on (IG)
  • Battery voltage is 10 V or higher
  • No communication between engine control unit and transmission control unit

ECM

Comes on

DTC stored

SAE Code: U0101

MONITOR STRATEGY

Related DTCs

U0101: Lost communication with TCM (verify communication)

Required Sensors/Components (Main)

ECM

Required Sensors/Components (Related)

-

Frequency of Operation

Continuous

Duration

1.25 seconds

MIL Operation

Immediate

Sequence of Operation

None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever the following DTCs are not stored

None

All of the following conditions are met

-

Battery voltage

10 V or higher

Engine switch

On (IG)

Starter

Off

TYPICAL MALFUNCTION THRESHOLDS

Communication signal

Lost communication with transmission control unit

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 Techstream to the DLC3.
  2. Turn the engine switch on (IG).
  3. Turn the Techstream on.
  4. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
  5. Turn the engine switch off and wait for at least 30 seconds.
  6. Turn the engine switch on (IG).
  7. Turn the Techstream on.
  8. Wait 5 seconds or more [A].
  9. Enter the following menus: Powertrain / Engine / Trouble Codes [B].
  10. Read the 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: U010187.
  13. Check the DTC judgment result.

    Techstream 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 is NORMAL, the system is normal.
    • If the judgment result is ABNORMAL, the system has a malfunction.
    • If the judgment result is INCOMPLETE, perform steps [A] through [B] again.
    • [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 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

HINT:

Read freeze frame data using the Techstream. 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.

CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC U010187)

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus: System Select / Health Check.

(e) Read the DTCs.

Result

Proceed to

DTC U010187 is output

A

DTC U010187 and other DTCs are output

B

HINT:

If any DTCs other than U010187 are output, troubleshoot those DTCs first.

A

REPLACE ECM

B

GO TO DTC CHART
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