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

Toyota Venza Service Manual / Networking / Can Communication System / Lost Communication with ECM / PCM (U0100)

DESCRIPTION

DTC No.	DTC Detection Condition	Trouble Area
U0100	No communication from the ECM continues.	ECM main wire or connector Power source circuit of ECM ECM

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Turn the ignition switch off before measuring the resistances between CAN bus main wires and between CAN bus branch wires.
Turn the ignition switch off before inspecting CAN bus wires for a ground short.
After the ignition switch is turned off, check that the key reminder warning system and light reminder warning system are not operating.
Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the ignition switch, any other switches or the doors. If any doors need to be opened in order to check connectors, open the doors and leave them open.

HINT:

Operating the ignition switch, any other switches or a door triggers related ECU and sensor communication on the CAN. This communication will cause the resistance value to change.
Even after DTCs are cleared, if a DTC is stored again after driving the vehicle for a while, the malfunction may be occurring due to vibration of the vehicle. In such a case, wiggling the ECUs or wire harness while performing the inspection below may help determine the cause of the malfunction.

PROCEDURE

1.	RECONFIRM DTC OUTPUT

(a) Reconfirm DTCs.

HINT:

If CAN power management bus DTC U1002 is output from the power management control ECU (Techstream display: PM2 Gateway), troubleshoot for U1002 and check for malfunctions in the power management main bus circuit.

Result	Proceed to
U1002 is not output from power management control ECU (Techstream display: PM2 Gateway)	A
U1002 is output from power management control ECU (Techstream display: PM2 Gateway)	B

REPAIR CIRCUITS INDICATED BY OUTPUT DTCS

2.	CHECK FOR OPEN IN CAN BUS WIRES (ECM MAIN WIRE/POWER MANAGEMENT BUS)

(a) Turn the ignition switch off.

(b) Disconnect the ECM connector.

Text in Illustration

for 1AR-FE

for 2GR-FE

Front view of wire harness connector

(to ECM)

Standard Resistance:

Tester Connection	Condition	Specified Condition
A49-12 (CANP) - A49-4 (CANN)*1	Ignition switch off	108 to 132 Ω
A41-8 (CANP) - A41-9 (CANN)*2	Ignition switch off	108 to 132 Ω

*1: for 1AR-FE

*2: for 2GR-FE

REPAIR OR REPLACE CAN BUS MAIN WIRE OR CONNECTOR (ECM MAIN WIRE)

3.	CHECK ECM POWER SOURCE CIRCUIT

(a) Check the ECM power source circuit.

HINT:

for 2GR-FE (See page ).

for 2AR-FE (See page ).

Result	Proceed to
OK (for 2GR-FE)	A
OK (for 2AR-FE)	B
NG	C

HINT:

If there is no abnormality in the ECM power source circuit, replace the ECM.

REPLACE ECM

REPAIR OR REPLACE ECM POWER SOURCE CIRCUIT

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