Toyota Venza: Lost Communication with TCM (U0101)

Toyota Venza Service Manual / 1ar-fe Engine Control / Sfi System / Lost Communication with TCM (U0101)

DESCRIPTION

The Transmission Control Module (TCM) and ECM perform 2-way communication with each other via the Controller Area Network (CAN). The TCM sends signals to the ECM concerning required engine speed, required engine torque, warning indicators in the combination meter, DTCs and other data. The ECM sends signals to the TCM concerning engine speed, opening angle of the throttle valve, temperature of intake air, temperature of engine coolant, engine torque and other data. If the TCM cannot communicate with the ECM, the TCM will conclude that there is a malfunction in the CAN system, illuminate the MIL and set a DTC.

DTC No.	DTC Detection Condition	Trouble Area
U0101	Following conditions are met for 1.25 seconds (1 trip detection logic): Ignition switch ON Battery voltage 10.5 V or more No intercommunication between ECM and TCM	ECM to TCM circuit TCM ECM

MONITOR STRATEGY

Related DTCs	U0101: Lost Communication with TCM
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 following DTCs are not present	None
All of the following conditions are met	-
Battery voltage	10.5 V or more (More than 1 second)
Ignition switch	ON
Starter	Off

TYPICAL MALFUNCTION THRESHOLDS

Communication signal

Lost communication with TCM

CONFIRMATION DRIVING PATTERN

Connect the Techstream to the DLC3.
Turn the ignition switch to ON and turn the Techstream on.
Clear the DTCs (even if no DTCs are stored, perform the Clear DTC procedure) (See page ).

Turn the ignition switch off and wait for at least 30 seconds.
Turn the ignition switch to ON and turn the Techstream on.
Wait 5 seconds or more.
Enter the following menus: Powertrain / Engine / Trouble Codes.
Read the Pending DTCs.
HINT:
- If a pending DTC is output, the system is malfunctioning.
- If a pending DTC is not output, perform the following procedure.
Enter the following menus: Powertrain / Engine / Utility / All Readiness.
Input the DTC: U0101.

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's 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 test result is INCOMPLETE or N/A and no pending DTC is output, perform a universal trip and check for permanent DTCs (See page ).
HINT:
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

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

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 OTHER DTC OUTPUT (IN ADDITION TO DTC U0101)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

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

(e) Read the DTCs.

Result	Proceed to
DTC U0101 is output	A
DTC U0101 and other DTCs are output	B

HINT:

If any DTCs other than U0101 are output, troubleshoot those DTCs first.

GO TO DTC CHART

2.	INSPECT ECU POWER SOURCE CIRCUIT (TCM POWER SOURCE)

(a) Disconnect the TCM connector.

(b) Turn the Ignition switch to ON.

Standard Voltage:

Tester Connection	Condition	Specified Condition
B40-1 (BATT) - B40-8 (E1)	Always	11 to 14 V
B40-18 (+B) - B40-8 (E1)	Ignition switch ON	11 to 14 V

Text in Illustration

*a	Front view of wire harness connector (to TCM)

Result	Proceed to
OK	A
NG (for U760E)	B
NG (for U760F)	C

GO TO TCM POWER SOURCE CIRCUIT

3.	CHECK HARNESS AND CONNECTOR (ECM - TCM)

(a) Disconnect the TCM connector.

(b) Disconnect the ECM connector.

Standard Resistance (Check for Open):

Tester Connection	Condition	Specified Condition
B40-6 (CAN+) - B58-24 (CAN+)	Always	Below 1 Ω
B40-7 (CAN-) - B58-1 (CAN-)	Always	Below 1 Ω

Standard Resistance (Check for Short):

Tester Connection	Condition	Specified Condition
B40-6 (CAN+) or B58-24 (CAN+) - Body ground	Always	10 kΩ or higher
B40-7 (CAN-) or B58-1 (CAN-) - Body ground	Always	10 kΩ or higher

Result	Proceed to
OK (for U760E)	A
OK (for U760F)	B
NG	C

GO TO STEP 5

REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - TCM)

4.	REPLACE TCM

(a) Replace the TCM (for U760E) (See page
).

GO TO STEP 6

5.	REPLACE TCM

(a) Replace the TCM (for U760F) (See page
).

6.	CHECK WHETHER DTC OUTPUT RECURS (DTC U0101)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

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

(e) Read the DTCs.

Result	Proceed to
DTC is not output	A
DTC U0101 is output	B

END

REPLACE ECM

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