Last Modified: 05-13-2024 6.11:8.1.0 Doc ID: RM1000000026FM3
Model Year Start: 2023 Model: Corolla Hatchback Prod Date Range: [09/2022 - 11/2022]
Title: K120 / K121 (CVT): K120 CONTINUOUSLY VARIABLE TRANSAXLE SYSTEM: U010087; Lost Communication with ECM/PCM "A" Missing Message; 2023 MY Corolla Corolla Hatchback [09/2022 - 11/2022]

DTC

U010087

Lost Communication with ECM/PCM "A" Missing Message

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

for TMMMS Made

The monitor will run whenever the following DTCs are not stored

None

Battery voltage (1 sec. or more)

10.5 V or more

Engine switch

On (IG)

Starter

OFF

for TMC Made

The monitor will run whenever the following DTCs are not stored

None

Battery voltage (1 sec. or more)

10.5 V or more

Engine switch

On (IG)

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 2023 MY Corolla Corolla Hatchback [09/2022 - 11/2022]; K120 / K121 (CVT): K120 CONTINUOUSLY VARIABLE TRANSAXLE SYSTEM: DTC CHECK / CLEAR

  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 3 minutes or more.
  5. Turn the engine switch on (IG) and turn the Techstream on.
  6. Wait for 3 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.

WIRING DIAGRAM

for TMMMS Made
for TMC Made

CAUTION / NOTICE / HINT

NOTICE:

  • Perform the universal trip to clear permanent DTCs.

    Click here 2023 MY Corolla Corolla Hatchback [09/2022 - 11/2022]; K120 / K121 (CVT): K120 CONTINUOUSLY VARIABLE TRANSAXLE SYSTEM: DTC CHECK / CLEAR

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

    Click here 2023 MY Corolla Corolla Hatchback [09/2022 - 11/2022]; K120 / K121 (CVT): K120 CONTINUOUSLY VARIABLE TRANSAXLE SYSTEM: PRECAUTION

  • Check that no DTCs are stored after performing initialization.

    Click here 2023 MY Corolla Corolla Hatchback [09/2022 - 11/2022]; K120 / K121 (CVT): K120 CONTINUOUSLY VARIABLE TRANSAXLE SYSTEM: DTC CHECK / CLEAR

  • 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 engine switch on (IG).

(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)

Engine switch on (IG)

11 to 14 V

(d) Turn the engine 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) for TMMMS Made:

(1) Disconnect the A47 ECM connector.

(b) for TMC Made:

(1) Disconnect the C76 ECM connector.

(c) Disconnect the C80 TCM connector.

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

Standard Resistance (for TMMMS Made):

Tester Connection

Condition

Specified Condition

C80-18 (CAN+) - A47-7 (CANP)

Always

Below 1 Ω

C80-17 (CAN-) - A47-17 (CANN)

Always

Below 1 Ω

C80-18 (CAN+) or A47-7 (CANP) - Body ground

Always

10 kΩ or higher

C80-17 (CAN-) or A47-17 (CANN) - Body ground

Always

10 kΩ or higher

Standard Resistance (for TMC Made):

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

(e) Connect the C80 TCM connector.

(f) for TMMMS Made:

(1) Connect the A47 ECM connector.

(g) for TMC Made:

(1) Connect the C76 ECM connector.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - TCM)

OK

3.

REPLACE TCM

(a) Replace the TCM.

Click here 2020 - 2025 MY Corolla Corolla Hatchback [03/2019 -        ]; K120 / K121 (CVT): K120 TCM: COMPONENTS

NEXT

4.

PERFORM REGISTRATION AND INITIALIZATION

(a) Perform Registration and Initialization.

for Registration: Click here 2019 - 2025 MY Corolla Corolla Hatchback [06/2018 -        ]; K120 / K121 (CVT): K120 CONTINUOUSLY VARIABLE TRANSAXLE SYSTEM: REGISTRATION

for Initialization: Click here 2023 MY Corolla Corolla Hatchback [09/2022 - 11/2022]; K120 / K121 (CVT): K120 CONTINUOUSLY VARIABLE TRANSAXLE SYSTEM: INITIALIZATION

NEXT

5.

CHECK DTC OUTPUT (DTC U010087)

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Clear the DTCs.

Powertrain > Transmission > Clear DTCs

(e) Turn the engine switch off and wait for at least 30 seconds.

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

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

(h) 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

(a) Replace the ECM.

Click here 2023 MY Corolla Corolla Hatchback [09/2022 - 11/2022]; M20A-FKS (ENGINE CONTROL): ECM: COMPONENTS

NEXT

PERFORM INITIALIZATION