Toyota Venza manuals

Toyota Venza: 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.

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

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)


NG

REPAIR OR REPLACE HARNESS OR CONNECTOR


OK

2.

CHECK HARNESS AND CONNECTOR (TCM - ECM)

(a) Disconnect the TCM connector.


(b) Disconnect the ECM connector.

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

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

*1

Front view of wire harness connector

(to ECM)

*2

Front view of wire harness connector

(to TCM)


NG

REPAIR OR REPLACE HARNESS OR CONNECTOR


OK

3.

CHECK IF DTC OUTPUT RECURS

(a) Connect the Techstream to the DLC3.

(b) Clear the DTCs.

(c) Replace the TCM.

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


A

REPLACE ECM


B

REPLACE TCM

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