K120 / K121 (CVT): K120 CONTINUOUSLY VARIABLE TRANSAXLE SYSTEM: U010087; Lost Communication with ECM/PCM "A" Missing Message; 2023 - 2025 MY Corolla Corolla Hatchback [11/2022 - ]

Last Modified: 05-13-2024	6.11:8.1.0	Doc ID: RM1000000028EL6
Model Year Start: 2023	Model: Corolla Hatchback	Prod Date Range: [11/2022 - ]
Title: K120 / K121 (CVT): K120 CONTINUOUSLY VARIABLE TRANSAXLE SYSTEM: U010087; Lost Communication with ECM/PCM "A" Missing Message; 2023 - 2025 MY Corolla Corolla Hatchback [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

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

Connect the Techstream to the DLC3.
Turn the engine switch on (IG) and turn the Techstream on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the engine switch off and wait for 3 minutes or more.
Turn the engine switch on (IG) and turn the Techstream on.
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.
Enter the following menus: Powertrain / Transmission / Utility / All Readiness.
Input the DTC: U010087.

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

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 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) Disconnect the C76 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 C76 ECM connector.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - TCM)

OK

3.	REPLACE TCM

(a) Replace the TCM.

Click here

NEXT

4.	PERFORM REGISTRATION AND INITIALIZATION

(a) Perform Registration and Initialization.

for Registration: Click here

for Initialization: Click here

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

NEXT

PERFORM INITIALIZATION