Lexus RX (RX 350L, RX450h) 2016-2022 Repair Manual: Lost Communication with ECM/PCM "A" Missing Message (U010087)

DESCRIPTION

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

If there is a problem in this intercommunication, the ECM stores this DTC.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

Note

U010087

Lost Communication with ECM/PCM "A" Missing Message

1. Diagnosis Condition 2. Malfunction Status 3. Malfunction Time 4. Other

  • The engine switch is on (IG) and battery voltage is 10.5 V or more.
  • No intercommunication between engine control unit and transmission control unit
  • 1.25 seconds or more
  • 1-trip detection logic

ECM

Comes on

DTC stored

SAE Code: U0100

MONITOR STRATEGY

Related DTCs

U0100: Verify communication

Required Sensors/Components (Main)

ECM

Required Sensors/Components (Related)

-

Frequency of Operation

Continuous

Duration

1.25 sec.

MIL Operation

Immediately

Sequence of Operation

None

TYPICAL ENABLING CONDITIONS

The monitor will run whenever the following DTCs are not stored.

None

Battery Voltage

10.5 V or more

Engine switch

On (IG)

Starter

Off

TYPICAL MALFUNCTION THRESHOLDS

Communication signal

Lost communication with ECM/PCM

CONFIRMATION DRIVING PATTERN

HINT:

  • After repairs have been completed, clear the DTCs and then check that the vehicle has returned to normal by performing the following All Readiness check procedure.
  • 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) and turn the Techstream on.
  3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
  4. Turn the engine switch off and wait for 2 minutes or more.
  5. Turn the engine switch on (IG) and turn the Techstream on.
  6. Wait for 2 seconds or more with the engine switch on (IG). [*1]

    HINT:

    [*1] : Normal judgment procedure.

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

  7. Enter the following menus: Powertrain / Transmission / Utility / All Readiness.
  8. Input the DTC: U010087.
  9. 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

    N/A

    • Unable to perform DTC judgment
    • Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

    HINT:

    • If the judgment result shows NORMAL, the system is normal.
    • If the judgment result shows ABNORMAL, the system has a malfunction.
    • If the judgment result shows INCOMPLETE or N/A, perform the normal judgment procedure again.

CAUTION / NOTICE / HINT

NOTICE:

  • Perform the universal trip to clear permanent DTCs.

    Click here

  • Perform registration and/or initialization when parts related to the automatic transaxle are replaced.

    Click here

PROCEDURE

1.

CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC U010087)

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Transmission / Trouble Codes.

Powertrain > Transmission > Trouble Codes

(e) Read the DTCs using the Techstream.

Result

Proceed to

Only DTC U010087 is output

A

DTC U010087 and other DTCs are output

B

B

GO TO DTC CHART

A

2.

REPLACE ECM

(a) Replace the ECM.

Click here

NEXT

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