CAN COMMUNICATION SYSTEM FAIL-SAFE CHART

  1. FAIL-SAFE FUNCTION

    1. When communication fails in any of the CAN bus lines (communication lines), a fail-safe function(s) will operate. The fail-safe function that is specified for each system operates to prevent those systems from malfunctioning.

    2. The following table shows the effects on each system when communication is impossible. (For further details, see the pages for each system.)

      Function

      Control Master

      System Related

      Fail-safe Operation

      Driver Detectable

      DTC Detection

      (ECU that stored DTC)

      Anti-lock Brake System Control

      • Prevents the wheels from locking during sudden stops.

      Skid control ECU (brake actuator assembly)

      -

      • During control:

        When backup control (stabilizing the vehicle) is complete, the system changes to normal braking and prohibits control.

      • Not during control:

        Control cannot be performed.

      • Brake warning light illuminates.

      • ABS warning light illuminates.

      U0073

      (Skid control ECU (brake actuator assembly))

      Vehicle Stability Control / Traction Control

      • Suppresses vehicle instability, such as sliding sideways when cornering and wheel slippage when accelerating from rest.

      Skid control ECU (brake actuator assembly)

      • ECM

      • Airbag sensor assembly

      • Steering sensor (spiral cable sub-assembly)

      • During control:

        When backup control (stabilizing the vehicle) is complete, the system changes to normal braking and prohibits control.

      • Not during control:

        Control cannot be performed.

      • Brake warning light illuminates.

      • ABS warning light illuminates.

      • Slip indicator light illuminates.

      U0073

      U0100

      U0123

      U0126

      (Skid control ECU (brake actuator assembly))

      Hill-start Assist Control

      • Maintains the brake hydraulic pressure to the 4 wheels for 2 seconds with the brake pedal released when starting off on an uphill.

      Skid control ECU (brake actuator assembly)

      • ECM

      • Airbag sensor assembly

      • Steering sensor (spiral cable sub-assembly)

      • During control:When backup control (depressurization control) is complete, further control cannot be performed.

      • Not during control:Control cannot be performed.

      • During control: Depressurization control has completed, further hill-start assist control is prohibited.

      • Not during control: Hill-start assist control does not start.

      • Brake warning light illuminates.

      • ABS warning light illuminates.

      • Slip indicator light illuminates.

      U0073

      U0100

      U0123

      U0126

      (Skid control ECU (brake actuator assembly))

      Air Conditioning Control

      • Corrects engine speed, such as for idle up.

      • Controls outlet air temperature, outlet mode change and airflow volume based on engine coolant temperature signal.

      Air conditioning control assembly

      ECM

      Control is performed based on default coolant temperature of 0°C (0°F).

      -

      U11DB

      (Air conditioning control assembly)

      Panel Dimming Control

      • Display dimming control.

      Air conditioning control assembly

      Combination meter assembly

      Automatic dimming control for displays does not operate when taillights are turned on.

      -

      -

      Ambient Temperature Correction Control

      • Air conditioning system operation control based on vehicle speed.

      Air conditioning control assembly

      Combination meter assembly

      Control is performed based on default vehicle speed of 0 km/h (0 mph).

      -

      U11DA

      (Air conditioning control assembly)

      Air Conditioning Control

      • Displays the set temperature, air outlet selection, etc.

      Radio and display receiver assembly

      Combination meter assembly

      Display becomes black (only measurement units are displayed).

      -

      U0155

      (Radio and display receiver assembly)

      Fuel Consumption Display

      • Displays graph of fuel consumption per minute and history of total fuel consumption.

      Radio and display receiver assembly

      • ECM

      • Skid control ECU (brake actuator assembly)

      • Combination meter assembly

      Display is not updated.

      -

      U0100

      U0129

      U0155

      (Radio and display receiver assembly)

      Electrical Load Control

      • Perform idle up according to electric load.

      ECM

      Power steering ECU assembly

      Idle up according to the electrical load is not performed.

      Engine idle speed changes.

      -

      Air Conditioning Cooperative Operation

      • Performs idle up according to compressor load.

      ECM

      Air conditioning control assembly

      Air conditioning system does not use cooperative controls.

      Air conditioning system does not operate.

      -

      Charge Control

      • Performs idle up according to charging request.

      ECM

      Air conditioning control assembly

      • Idle up according to charging request is not performed.

      • Charging control is not prohibited.

      • Idle up according to charging request is not performed.

      • Tail lights flicker and blower airflow changes.

      -

      Steering Assist Calculation

      • Changes the assist force according to the vehicle speed.

      Power steering ECU assembly

      Skid control ECU (brake actuator assembly)

      • Control continues temporarily with a set speed of 70 km/h (43 mph) as the system is unable to recognize the actual vehicle speed.

      • The steering wheel feels heavy below vehicle speeds of 70 km/h (43 mph) and feels light at vehicle speeds exceeding 70 km/h (43 mph).

      EPS warning light illuminates.

      U0129

      (Power steering ECU assembly)

      Steering Assist Compensation Control

      • Provides steering assist with compensation amount based on vehicle speed.

      Power steering ECU assembly

      Skid control ECU (brake actuator assembly)

      Control is performed based on a default vehicle speed of approximately 70 km/h (43 mph).

      EPS warning light illuminates.

      U0129

      (Power steering ECU assembly)

      Entry Function

      • Warning.

      Certification ECU (smart key ECU assembly)

      • ECM

      • Combination meter assembly

      -

      • Warning functions (key confinement, key not in vehicle, key reminder, etc.) do not operate and key confinement prevention control does not operate.

      U0100

      U0155

      (Certification ECU (smart key ECU assembly))

      Engine Start/Stop Switch (Power Source Mode Change)

      • Using start/stop switch signal as trigger, changes power source mode automatically and requests starter operation when conditions are met.

      Certification ECU (smart key ECU assembly)

      ECM

      -

      A message urging engine start operation is not displayed when required.

      U0100

      U0155

      (Certification ECU (smart key ECU assembly))

      Engine Start Control

      • Allows the engine to start by pressing the engine switch once.

        (Cranking hold)

      Certification ECU (smart key ECU assembly)

      ECM

      Cranking is stopped when engine starting is judged based on an engine speed signal received via direct line.

      -

      U0100

      (Certification ECU (smart key ECU assembly))

      Vehicle Speed Display

      • Displays the vehicle speed on the speedometer according to the vehicle speed signal from skid control ECU (brake actuator assembly).

      Combination meter assembly

      Skid control ECU (brake actuator assembly)

      Control is performed based on signal value of 0.

      The needle points at 0 km/h (0 mph).

      U0129

      (Combination meter assembly)

      Stop and Start System

      • Stops the engine when the vehicle is stationary.

      Engine stop and start ECU

      • Air conditioning control assembly

      • Skid control ECU (brake actuator assembly)

      • ECM

      • Power steering ECU assembly

      • Airbag sensor assembly

      • Combination meter assembly

      • When driving in eco drive mode, the engine starts.

      • When not driving in eco drive mode, eco drive cannot be performed.

      Stop and start indicator light blinks.

      U0100

      U0121

      U0131

      U0151

      U0155

      U0164

      (Engine stop and start ECU)