Toyota Corolla Cross Owners & Service Manuals

Toyota Corolla Cross: Lost Communication with ECM/PCM "A" Missing Message (U010087)

Toyota Corolla Cross (2022-2024) Service Manual / Drivetrain / K120 (cvt) / Continuously Variable Transaxle System / Lost Communication with ECM/PCM "A" Missing Message (U010087)

DESCRIPTION

The TCM communicates with the ECM via CAN communication.

If a problem occurs in this communication, the TCM stores this DTC.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

Note

U010087

Lost Communication with ECM/PCM "A" Missing Message

No communication between the TCM and ECM for 1.25 seconds or more (1-trip detection logic)

  • Harness and connector
  • ECM
  • TCM

Comes on

DTC stored

SAE Code:

U0100

MONITOR STRATEGY

Related DTCs

U0100: Lost communication with ECM/PCM Verify communication

Required sensors/Components

ECM

Frequency of Operation

Continuous

Duration

1.25 sec.

MIL Operation

Immediate

Sequence of Operation

None

TYPICAL ENABLING CONDITIONS

The monitor will run whenever the following DTCs are not stored

None

Auxiliary battery voltage (1 sec. or more)

10.5 V or more

Ignition switch

ON

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. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
  2. Turn the ignition switch off and wait for 3 minutes or more.
  3. Turn the ignition switch to ON and turn the GTS on.
  4. Wait for 3 seconds or more with the ignition switch to ON. [*1]

    HINT:

    [*1]: Normal judgment procedure.

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

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

    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.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • Perform the universal trip to clear permanent DTCs.

    Click here

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

    Click here

  • Check that no DTCs are stored after performing initialization.

    Click here

  • Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE

1.

CHECK TERMINAL VOLTAGE (POWER SOURCE OF TCM)

(a) Disconnect the C80 TCM connector.

(b) Turn the ignition switch to ON.

(c) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection

Condition

Specified Condition

C80-1 (+B) - C80-2 (E1)

Ignition switch ON

11 to 14 V

(d) Turn the ignition switch off.

(e) Connect the C80 TCM connector.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE OF TCM)

OK

2.

CHECK HARNESS AND CONNECTOR (ECM - TCM)

(a) Disconnect the A47 ECM connector.

(b) Disconnect the C80 TCM connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

C80-18 (CAN+) - C76-40 (CANP)

Always

Below 1 Ω

C80-17 (CAN-) - C76-39 (CANN)

Always

Below 1 Ω

C80-18 (CAN+) or C76-40 (CANP) - Body ground

Always

10 kΩ or higher

C80-17 (CAN-) or C76-39 (CANN) - Body ground

Always

10 kΩ or higher

(d) Connect the C80 TCM connector.

(e) Connect the A47 ECM connector.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - TCM)

OK

3.

REPLACE TCM

Click here

NEXT

4.

PERFORM REGISTRATION AND INITIALIZATION

for Registration: Click here

for Initialization: Click here

NEXT

5.

CHECK DTC OUTPUT (DTC U010087)

(a) Clear the DTCs.

Powertrain > Transmission > Clear DTCs

(b) Turn the ignition switch off and wait for at least 30 seconds.

(c) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

(d) Enter the following menus:

(e) Read the DTCs.

Powertrain > Transmission > Trouble Codes

Result

Proceed to

DTCs are not output

A

DTC U010087 is output

B

A

END

B

6.

REPLACE ECM

Click here

NEXT

PERFORM INITIALIZATION

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