Toyota Venza Quiz
Networking

Lost Communication with ECM / PCM (U0100)

In this manual: Networking
Introduction — 15Maintenance — 8Audio / Video — 102Garage Door Opener — 8Navigation / Multi Info Display — 81Park Assist / Monitoring — 50Brake (front) — 7Brake (rear) — 7Brake Control / Dynamic Control Systems — 79Brake System (other) — 28Parking Brake — 22Axle And Differential — 44Drive Shaft / Propeller Shaft — 24Mf1a Transfer / 4wd / Awd — 46U660e Automatic Transmission / Transaxle — 1241ar-fe Cooling — 311ar-fe Emission Control — 101ar-fe Engine Control — 1331ar-fe Engine Mechanical — 441ar-fe Fuel — 311ar-fe Intake / Exhaust — 211ar-fe Lubrication — 111ar-fe Starting — 16Cruise Control — 241ar-fe Battery / Charging — 162gr-fe Battery / Charging — 17Networking — 67Power Distribution — 8Power Assist Systems — 34Steering Column — 37Steering Gear / Linkage — 29Alignment / Handling Diagnosis — 4Front Suspension — 39Rear Suspension — 35Tire / Wheel — 4Tire Pressure Monitoring — 35Door / Hatch — 83Exterior Panels / Trim — 56Horn — 4Lighting (ext) — 89Mirror (ext) — 36Sliding Roof / Convertible — 26Window / Glass — 87Wiper / Washer — 30Door Lock — 85Heating / Air Conditioning — 82Interior Panels / Trim — 20Lighting (int) — 37Meter / Gauge / Display — 41Mirror (int) — 9Power Outlets (int) — 10Seat — 84Seat Belt — 43Supplemental Restraint Systems — 131Theft Deterrent / Keyless Entry — 155
~3min read
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

B

REPAIR CIRCUITS INDICATED BY OUTPUT DTCS
A

  1. 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

*A

for 1AR-FE

*B

for 2GR-FE

*1

Front view of wire harness connector

(to ECM)

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

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


NG

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

  1. 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.


A

REPLACE ECM

B

REPLACE ECM

C

REPAIR OR REPLACE ECM POWER SOURCE CIRCUIT

Test yourself

A quick Toyota Venza quiz: every answer comes with an explanation and a link to the manual page.