Toyota Venza: Lost Communication with ECM / PCM "A" (U0100)

Toyota Venza Service Manual / U660e Automatic Transmission / Transaxle / Automatic Transaxle System / Lost Communication with ECM / PCM "A" (U0100)

DESCRIPTION

The engine control unit communicates with the TCM using the Controller Area Network (CAN).

If there is a problem in this communication, the TCM sets a DTC.

DTC No.	DTC Detection Condition	Trouble Area
U0100	Following conditions are met for 1.25 seconds (1 trip detection logic): Ignition switch ON Battery voltage is 10.5 V or more No communication between the engine control ECU and TCM	Harness and connector ECM TCM

MONITOR STRATEGY

Related DTCs	U0100: Verify communication
Required Sensors/Components (Main)	TCM
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 not present	None
Battery Voltage	10.5 V or more
Ignition Switch	ON
Starter	OFF

TYPICAL MALFUNCTION THRESHOLDS

Communication between TCM and ECM

No communication

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Perform the universal trip to clear permanent DTCs (See page ).

HINT:

Refer to inspection procedure for CAN communication system.
If the CAN communication malfunctions, the TCM cannot receive the current data from the ECM. In this case, the freeze frame data output from the TCM has not been updated, so the data will not be useful for the inspection. However, reading the Data List as the first step in troubleshooting is effective to find malfunctions.
The malfunction area can be checked using the Bus Check function on the Techstream (See page ).

PROCEDURE

1.	CHECK ECU TERMINAL VOLTAGE (+B AND E1 TERMINALS)

(a) Disconnect the TCM connector.

(b) Turn the ignition switch to ON.

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
B40-18 (+B) - B40-8 (E1)	Ignition switch ON	9 to 14 V

(d) Turn the ignition switch off.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
B40-8 (E1) - Body ground	Always	Below 1 Ω

Text in Illustration

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

REPAIR OR REPLACE HARNESS OR CONNECTOR

2.	CHECK HARNESS AND CONNECTOR (TCM - ECM)

(a) Disconnect the TCM connector.

(b) Disconnect the ECM connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
B40-6 (CAN+) - B39-24 (CAN+)	Always	Below 1 Ω
B40-7 (CAN-) - B39-1 (CAN-)	Always	Below 1 Ω
B40-6 (CAN+) or B39-24 (CAN+) - Body ground or other terminals	Always	1 MΩ or higher
B40-7 (CAN-) or B39-1 (CAN-) - Body ground or other terminals	Always	1 MΩ or higher

Text in Illustration

Front view of wire harness connector

(to ECM)

Front view of wire harness connector

(to TCM)

REPAIR OR REPLACE HARNESS OR CONNECTOR

3.	CHECK IF DTC OUTPUT RECURS

(a) Connect the Techstream to the DLC3.

(b) Clear the DTCs.

HINT:

Replace the TCM with a TCM from a normally functioning vehicle of the same model.

(d) Start the engine.

(e) Read the DTCs.

Display (DTC Output)	Proceed to
U0100	A
No DTC	B

REPLACE ECM

REPLACE TCM

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