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)

      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.

      • Corrects engine coolant temperature map and changes compressor lock judgment value.

      Air conditioning amplifier assembly ECM Control is performed based on default coolant temperature of 80°C (176°F). -

      U0100

      (Air conditioning amplifier assembly)

      Compressor Control


      • Judges compressor lock according to engine speed.

      Air conditioning amplifier assembly ECM Control is performed based on default engine speed of 0 rpm. -

      U0100

      (Air conditioning amplifier assembly)

      Simple Load Control


      • Performs electric load control according to load control level signal.

      Air conditioning amplifier assembly Power steering ECU with motor assembly Load control is not performed. -

      U0131

      (Air conditioning amplifier assembly)

      Panel Control


      • Controls air conditioning system operation state display and air conditioning control panel switch indicator output based on air conditioning control panel switch operation.

      • If automatic circulation control is available, changes the air inlet mode to FRESH or RECIRCULATION mode based on information from the smog ventilation sensor.

      Air conditioning amplifier assembly Multi-media module receiver assembly Air inlet mode does not change. -

      U0163

      (Air conditioning amplifier assembly)

      Panel Dimming Control


      • Outputs dimmer signal to LIN connected panels according to display dimmer signal.

      Air conditioning amplifier assembly Main body ECU (Multiplex network body ECU) Dimming mode and non-dimming mode cannot be switched. -

      U0142

      (Air conditioning amplifier assembly)

      Destination Identification Control


      • Changes air conditioning control pattern according to destination.

      Air conditioning amplifier assembly Main body ECU (Multiplex network body ECU) Maintains the latest state. -

      U0142

      (Air conditioning amplifier assembly)

      Ambient Temperature Correction Control


      • Switches air conditioning system operation condition and corrects value of displayed ambient temperature according to vehicle speed signal.

      Air conditioning amplifier assembly Combination meter assembly Control is performed based on default vehicle speed of 0 km/h (0 mph).
      • Correction level for displayed ambient temperature declines.

      • Correction level for outlet airflow declines.

      U0155

      (Air conditioning amplifier assembly)

      Air Conditioning Eco Mode Control


      • Limits air conditioning system control.

      Air conditioning amplifier assembly ECM Maintains the latest state (Maintained in normal condition after reset). -

      U0100

      (Air conditioning amplifier assembly)

      Electric Load Control


      • Performs idle up according to electric load.

      ECM
      • Air conditioning amplifier assembly

      • Main body ECU (Multiplex network body ECU)

      • Power steering ECU with motor assembly

      Idle up according to electric load is not performed. Not possible. (Idle speed changes) -

      Air Conditioning Cooperative Operation


      • Performs idle up according to compressor load.

      • Performs air conditioning cut control.

      ECM Air conditioning amplifier assembly Air conditioning system does not use cooperative controls. (Idle up is not performed.) Air conditioning system does not operate. -

      PTC Heater


      • When there is a heat demand signal that requires operation of the PTC heater (including heating from coolant), idle up is performed.

      ECM Air conditioning amplifier assembly Engine idle speed changes.

      Heating performance deteriorates.

      PTC heater does not operate.

      -

      Charge Control


      • Performs idle up according to charging request.

      ECM
      • Air conditioning amplifier assembly

      • Main body ECU (Multiplex network body ECU)

      Idle up according to charging request is not performed. Taillights flicker and blower airflow changes. -

      Eco Control


      • Adjusts throttle response in consideration of actual fuel economy.

      ECM
      • Air conditioning amplifier assembly

      • Main body ECU (Multiplex network body ECU)

      • Combination meter assembly

      Eco mode does not operate. - -

      Cruise Control


      • Controls vehicle speed by adjusting throttle valve angle automatically.

      ECM
      • Brake actuator assembly (Skid control ECU)

      • Driving support ECU assembly

      • Combination meter assembly

      Cruise control does not operate.
      • Displays messages on the multi-information display.

      • Cruise control indicator light (amber) illuminates.

      -

      Power Steering Control


      • Calculates assist current according to torque sensor value and vehicle speed and drives motor.

      Power steering ECU with motor assembly
      • ECM

      • Brake actuator assembly (Skid control ECU)

      • Steering sensor

      When communication with ECM is interrupted:


      • Power steering assist not provided.

      When communication with skid control ECU is interrupted:


      • Control continues based on a default speed of 100 km/h (62 mph) because vehicle speed is unrecognizable. (Steering wheel feels heavy when the vehicle speed is below 100 km/ h (62 mph) and feels light at speeds above 100 km/h (62 mph).)

      EPS warning light illuminates.

      U0100

      U0129

      (Power steering ECU with motor assembly)

      Steering Assist Calculation


      • Changes assist force based on vehicle speed.

      Power steering ECU with motor assembly
      • Brake actuator assembly (Skid control ECU)

      • Airbag sensor assembly

      • Steering sensor

      Control continues based on a default speed of 100 km/h (62 mph) because vehicle speed is unrecognizable. (Steering wheel feels heavy when the vehicle speed is below 100 km/h (62 mph) and feels light at speeds above 100 km/h (62 mph).) EPS warning light illuminates.

      U0129

      (Power steering ECU with motor assembly)

      Assist Map Selection


      • Selects proper assist map according to destination, engine type, etc.

      Power steering ECU with motor assembly ECM Default map is used to assist because proper assist map cannot be selected. (Steering feel may be different.) EPS warning light illuminates.

      C1582

      (Power steering ECU with motor assembly)

      Steering/Steering angle sensor initialization and zero point learning. Power steering ECU with motor assembly
      • Brake actuator assembly (Skid control ECU)

      • Airbag sensor assembly

      • Steering sensor

      Steering initialization and zero point learning are not performed. EPS warning light illuminates.

      U0129

      (Power steering ECU with motor assembly)

      Lane Departure Alert System


      • Warns when vehicle is deviating from its lane.

      Lane departure warning camera
      • ECM

      • Airbag sensor assembly

      • Brake actuator assembly (Skid control ECU)

      • Main body ECU (Multiplex network body ECU)

      • Combination meter assembly

      • Driving support ECU assembly

      Lane recognition and buzzer warning are canceled.
      • Displays messages on the multi-information display.

      • LDA indicator light not illuminates.

      U0101

      U0104

      U0123

      U0129

      U0142

      U0155

      (Lane departure warning camera)

      Automatic High Beam System


      • Controls high beam on/off.

      Lane departure warning camera
      • ECM

      • Airbag sensor assembly

      • Brake actuator assembly (Skid control ECU)

      • Main body ECU (Multiplex network body ECU)

      Maintains the same condition. Displays messages on the multi-information display.

      U0101

      U0123

      U0129

      U0142

      (Lane departure warning camera)

      Vehicle Speed Display Combination meter assembly Brake actuator assembly (Skid control ECU) None
      • Needle of speedometer remains at 0 km/h (0 mph).

      • Drive monitor calculation is stopped.

      U0129

      (Combination meter assembly)

      Tachometer Display Combination meter assembly ECM None
      • Needle of tachometer remains at 0 rpm.

      • Drive monitor calculation is stopped.

      U0100

      (Combination meter assembly)

      Airbag Warning


      • Airbag warning light control

      Combination meter assembly Airbag sensor assembly None Airbag warning light illuminates.

      U0151

      (Combination meter assembly)

      EPS Warning


      • EPS warning light control

      Combination meter assembly Power steering ECU with motor assembly None EPS warning light illuminates.

      U0131

      (Combination meter assembly)

      Vehicle Customization


      • Displays vehicle customization items on the multi-information display based on the display request from the main body ECU (multiplex network body ECU).

      Combination meter assembly Main body ECU (Multiplex network body ECU) None Multi-information display does not display vehicle customization items.

      U0142

      (Combination meter assembly)

      SLIP Warning


      • SLIP warning light control

      Combination meter assembly Brake actuator assembly (Skid control ECU) None SLIP indicator illuminates. -
      Engine Coolant Temperature Receiver Gauge Control Combination meter assembly ECM None Needle of engine coolant temperature receiver gauge is at the middle or below. -

      Tire Pressure Monitor System


      • Tire pressure warning light control

      Combination meter assembly Main body ECU (Multiplex network body ECU) None Tire pressure warning light illuminates. -

      Tire Pressure Monitor System


      • Displays tire pressure on the multi-information display.

      Combination meter assembly Main body ECU (Multiplex network body ECU) None Tire pressure is not displayed. -
      ABS Control Brake actuator assembly (Skid control ECU) Airbag sensor assembly
      • When control is being performed:

      When back-up control (vehicle behavior stabilization) is complete, braking returns to normal operation and further control is prohibited.


      • When control is not being performed:

      Control will not be started.


      • Brake warning light illuminates.

      • ABS warning light illuminates.

      • SLIP indicator illuminates.

      U0073

      U0124

      (Brake actuator assembly (Skid control ECU))

      TRC/VSC Control Brake actuator assembly (Skid control ECU)
      • Airbag sensor assembly

      • Steering sensor

      • ECM

      • Power steering ECU with motor assembly


      • When control is being performed:

      When back-up control (vehicle behavior stabilization) is complete, braking returns to normal operation and further control is prohibited.


      • When control is not being performed:

      Control will not be started.


      • Brake warning light illuminates.

      • ABS warning light illuminates.

      • SLIP indicator illuminates.

      U0073

      U0100

      U0124

      U0126

      (Brake actuator assembly (Skid control ECU))

      Air Conditioning Control


      • Air conditioning control controls air conditioning functions such as set temperature adjustment, air outlet selection, etc. using the remote touch.

      Multi-media module receiver assembly Air conditioning amplifier assembly
      • When set temperature is shown on multi-display, set temperature display turns off.

      • Air conditioning function(s) are prohibited.

      A message indicating to check air conditioning amplifier connection appears on multi-display.

      U0073

      (Multi-media module receiver assembly)

      Fuel Consumption Display


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

      Multi-media module receiver assembly
      • ECM

      • Brake actuator assembly (Skid control ECU)

      • Combination meter assembly

      When communication with ECM or skid control ECU is interrupted:


      • Display is not updated.

      When communication with combination meter is interrupted:


      • Display is not updated.

      • Numeric part of driveable mileage is cleared.

      -

      U0100

      U0129

      U0155

      (Multi-media module receiver assembly)

      Destination Identification


      • Identifies destination based on destination and destination package information, and selects the time zone and language used for the display.

      Multi-media module receiver assembly Main body ECU (Multiplex network body ECU) Destination is identified based on information received before communication is interrupted. Time zone and language selection screen are different from actual destination.

      U0140

      (Multi-media module receiver assembly)

      Vehicle Customization Function


      • Allows changing of operation and control conditions for vehicle functions via multi-display operation.

      Multi-media module receiver assembly
      • Main body ECU (Multiplex network body ECU)

      • Certification ECU (Smart key ECU assembly)

      • Air conditioning amplifier assembly

      • Front power seat switch LH

      • Multiplex tilt and telescopic ECU

      When an application that uses phase 4 remote communication is activated (customization/remote diagnosis), the process will be performed regardless of main body ECU (multiplex network body ECU) remote communication permit/ prohibit state. Related customization items are not displayed or do not change to set values.

      U0073

      (Multi-media module receiver assembly)

      Rear View Monitor System


      • Displays images from the rear view camera.

      Multi-media module receiver assembly
      • ECM

      • Main body ECU (Multiplex network body ECU)

      None Screen does not change to the camera screen.

      U0100

      (Multi-media module receiver assembly)

      Rear View Monitor Control


      • Displays the guide lines based on the steering sensor and vehicle speed.

      Multi-media module receiver assembly
      • ECM

      • Steering sensor

      • Brake booster with master cylinder assembly (Skid control ECU)

      • Main body ECU (Multiplex network body ECU)


      • If a communication stop occurs when the expected course lines are being displayed, the expected course lines are cleared and "Guidance unavailable" is displayed on the bottom of the screen.

      • If a communication stop occurs when the display is in parallel parking guide mode, "Guidance unavailable" is displayed on the bottom of the screen.

      -

      U0100

      U0126

      U0129

      U0140

      (Multi-media module receiver assembly)

      Entry Function


      • Entry lock/unlock, entry luggage compartment open.

      • Warning.

      • Performs entry illumination (Interior illumination etc).


      • Main body ECU (Multiplex network body ECU)

      • Certification ECU (Smart key ECU assembly)


      • Main body ECU (Multiplex network body ECU)

      • Certification ECU (Smart key ECU assembly)

      • Combination meter assembly

      Entry unlock is performed again.
      • Entry lock/ unlock or entry luggage compartment open does not operate.

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

      • Entry illumination does not operate.

      U0100

      U0155

      U0327

      (Main body ECU (Multiplex network body ECU))

      U0100

      U0142

      U0155

      (Certification ECU (Smart key ECU assembly))

      Engine Switch Backlighting Control


      • Turns on/off engine switch illumination linked with interior lights etc.

      Certification ECU (Smart key ECU assembly) Main body ECU (Multiplex network body ECU) Engine switch backlighting does not illuminate according to interior lights operation. -

      U0142

      Certification ECU (Smart key ECU assembly)

      Door Lock


      • Controls key linked and automatic door lock/unlock function, key confinement prevention function, etc.

      Main body ECU (Multiplex network body ECU)
      • ECM

      • Airbag sensor assembly

      • Combination meter assembly


      • Speed sensitive automatic lock control does not occur.

      • Shift linked automatic lock control does not occur.

      • Shift linked automatic unlock control does not occur.

      • Automatic lock/ unlock cannot be changed.

      -

      U0100

      U0101

      U0151

      U0155

      (Main body ECU (Multiplex network body ECU))

      Display Automatic Dimming


      • Display dimming control.

      Main body ECU (Multiplex network body ECU) Combination meter assembly Automatic dimming control for displays does not operate when taillights are turned on. -

      U0155

      (Main body ECU (Multiplex network body ECU))

      Luggage Compartment Door Opener/luggage Compartment Door Open Control


      • (Accepts luggage compartment door opener request).

      Main body ECU (Multiplex network body ECU)
      • ECM

      • Combination meter assembly

      Luggage compartment door does not open. -

      U0100

      U0101

      U0155

      (Main body ECU (Multiplex network body ECU))

      Illumination Control Main body ECU (Multiplex network body ECU)
      • Certification ECU (Smart key ECU assembly)

      • ECM

      Interior lights turn off.

      When communication with certification ECU (smart key ECU assembly) is interrupted:


      • Interior lights do not turn off right after getting out of the vehicle.

      U0101

      U0327

      (Main body ECU (Multiplex network body ECU))

      Seat and Mirror Control Main body ECU (Multiplex network body ECU)
      • Front power seat switch LH

      • Outer mirror control ECU assembly (for driver side)

      • Outer mirror control ECU assembly (for front passenger side)

      • Multiplex tilt and telescopic ECU

      • Certification ECU (Smart key ECU assembly)

      • Combination meter assembly


      • Memory function does not operate.

      • Mirrors cannot be adjusted.

      -

      U0120

      U0199

      U0200

      U0208

      U0155

      U0327

      U1115

      (Main body ECU (Multiplex network body ECU))

      Entry Function/Wireless Control Certification ECU (Smart key ECU assembly) Main body ECU (Multiplex network body ECU) Entry lock/unlock control is not possible. -

      U0327

      (Main body ECU (Multiplex network body ECU))

      Daytime Running Light Control Main body ECU (Multiplex network body ECU) ECM Daytime running light control does not operate. -

      U0100

      (Main body ECU (Multiplex network body ECU))

      Vehicle Customization Main body ECU (Multiplex network body ECU)
      • Air conditioning amplifier assembly

      • Multi-media module receiver assembly

      • ECM

      • Clearance warning ECU assembly

      • Certification ECU (Smart key ECU assembly)

      • Combination meter assembly

      Vehicle customization functions do not operate. -

      U0155

      U0163

      U0327

      (Main body ECU (Multiplex network body ECU))

      Tire Pressure Monitor System


      • Monitors tire pressure, vehicle speed, etc., and illuminates indicator lights or displays a message on the multi-information display.

      Main body ECU (Multiplex network body ECU) Combination meter assembly - TPMS indicator light blinks and then illuminates.

      U0155

      (Main body ECU (Multiplex network body ECU))

      Automatic High Beam System


      • Controls high beam output automatically when the lane departure warning camera detects preceding or oncoming vehicles.

      Main body ECU (Multiplex network body ECU) Lane departure warning camera Maintains the same condition. Displays messages on the multi-information display.

      U0182

      (Main body ECU (Multiplex network body ECU))

      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.

      Main body ECU (Multiplex network body ECU)
      • Certification ECU (Smart key ECU assembly)

      • ECM

      • Brake actuator assembly (Skid control ECU)

      • Combination meter assembly

      - Engine start assist messages are not displayed on the multi-display.

      U0100

      Certification ECU (Smart key ECU assembly)

      Power Tilt and Power Telescopic Steering Column Control Multiplex tilt and telescopic ECU
      • Front power seat switch LH

      • Main body ECU (Multiplex network body ECU)

      • Combination meter assembly

      -
      • Driving position memory function is prohibited.

      • Auto away/return function is prohibited.

      U0142

      U0208

      (Multiplex tilt and telescopic ECU)

      Seat Position Memory System


      • Controls the seat position based on operation conditions.

      Front power seat switch LH
      • Main body ECU (Multiplex network body ECU)

      • ECM

      • Combination meter assembly

      • Certification ECU (Smart key ECU assembly)

      • Multiplex tilt and telescopic ECU

      Controls the seat position based on operation conditions. - -
      Mirror Surface Adjustment
      • Outer mirror control ECU assembly (for Driver side)

      • Outer mirror control ECU assembly (for Front passenger side)

      Main body ECU (Multiplex network body ECU) Mirror surface position cannot be memorized or recalled. -

      U0142

      (Outer mirror control ECU assembly)

      Mirror Heaters
      • Outer mirror control ECU assembly (for Driver side)

      • Outer mirror control ECU assembly (for Front passenger side)


      • Air conditioning amplifier assembly

      • Main body ECU (Multiplex network body ECU)

      Mirror heaters do not operate. - -
      Mirror Retract/Return Operation
      • Outer mirror control ECU assembly (for Driver side)

      • Outer mirror control ECU assembly (for Front passenger side)

      Main body ECU (Multiplex network body ECU) Mirrors cannot be retracted or returned. - -
      Reverse-shift Linked Door Mirror Operation
      • Outer mirror control ECU assembly (for Driver side)

      • Outer mirror control ECU assembly (for Front passenger side)

      Main body ECU (Multiplex network body ECU) Reverse-shift linked door mirror operation. - -
      Mirror Surface Position Memory and Recall
      • Outer mirror control ECU assembly (for Driver side)

      • Outer mirror control ECU assembly (for Front passenger side)

      Main body ECU (Multiplex network body ECU) Mirror surface position cannot be memorized or recalled. - -

      Seat Memory Switch Signal Forwarding


      • Transmits memory switch signal via the CAN bus

      Main body ECU (Multiplex network body ECU)
      • Outer mirror control ECU assembly (for Driver side)

      • Outer mirror control ECU assembly (for Front passenger side)

      Seat position memory settings cannot be memorized or recalled. - -

      Power Trunk Lid System


      • Opens/closes luggage compartment door automatically based on main switch operation and operation conditions.

      Luggage closer motor assembly
      • Main body ECU (Multiplex network body ECU)

      • ECM

      • Certification ECU (Smart key ECU assembly)

      • Combination meter assembly

      • Brake actuator assembly (Skid control ECU)


      • Automatic open function does not operate.

      • Automatic close function cannot reverse operation while operating.

      - -

      Luggage Compartment Door Closer System


      • Fully closes luggage compartment door automatically when it is ajar.

      Luggage closer motor assembly
      • Main body ECU (Multiplex network body ECU)

      • ECM

      • Certification ECU (Smart key ECU assembly)

      • Combination meter assembly

      • Brake actuator assembly (Skid control ECU)

      Automatic close function cannot reverse operation while operating. - -

      Courtesy Switch Signal Forwarding


      • Transmits courtesy switch signals of the luggage compartment door via the CAN bus.

      Luggage closer motor assembly Main body ECU (Multiplex network body ECU) - Door ajar warning light does not illuminate even though the luggage compartment door is open. -

      Dynamic Radar Cruise Control System


      • Accelerates or decelerates the vehicle to maintain the distance to the vehicle ahead.

      ECM
      • Airbag sensor assembly

      • Main body ECU (Multiplex network body ECU)

      • Steering sensor

      • Brake actuator assembly (Skid control ECU)

      • Driving support ECU assembly

      • Combination meter assembly

      Control stops
      • Displays messages on the multi-information display.

      • Cruise control indicator light (amber) illuminates.

      U0125

      U0126

      U0129

      (ECM)

      Pre-crash Safety System


      • Controls the seat belts and brakes immediately before a crash.

      Driving support ECU assembly
      • ECM

      • Airbag sensor assembly

      • Steering sensor

      • Brake actuator assembly (Skid control ECU)

      • Seat belt control ECU

      • Main body ECU (Multiplex network body ECU)

      Control stops.
      • Displays messages on the multi-information display.

      • PCS indicator light flashes.

      U0125

      U0126

      U0129

      U0142

      U1100

      (Driving support ECU assembly)

      Lexus Parking Assist-sensor System Control


      • Judges shift lever position.

      Clearance warning ECU assembly ECM Obstacle detection is stopped. -

      U0101

      (Clearance warning ECU assembly)

      Lexus Parking Assist-sensor System Control


      • Judges vehicle speed.

      Clearance warning ECU assembly Combination meter assembly Obstacle detection is stopped. -

      U0155

      (Clearance warning ECU assembly)

      Pre-crash Safety System

      (Operation Condition 1)


      • When the VSC system suddenly brakes or the vehicle is unable to be controlled while spinning or drifting, the seat belt control ECU receives buckle switch information from the center airbag sensor assembly and operates the pre-crash seat belts that retracts the seat belts to enhance the effect of the pretensioner.

      Seat belt control ECU
      • Airbag sensor assembly

      • Brake actuator assembly (Skid control ECU)

      • Main body ECU (Multiplex network body ECU)

      Control stops PCS indicator light flashes.

      U0129

      U0140

      U0151

      (Seat belt control ECU)

      Pre-crash Safety System

      (Operation Condition 2)


      • When the driving support ECU assembly has determined that a collision is unavoidable based on information from the millimeter wave radar sensor, the seat belt control ECU operates the pre-crash seat belts to enhance the effect of the pretensioner.

      Seat belt control ECU
      • Airbag sensor assembly

      • Brake actuator assembly (Skid control ECU)

      • Main body ECU (Multiplex network body ECU)

      • Driving support ECU assembly

      Control stops PCS indicator light flashes.

      U0129

      U0140

      U0151

      U1104

      (Seat belt control ECU)

      Blind Spot Monitor Control


      • Detects vehicle in blind spot of adjacent lane and informs driver.

      Blind spot monitor sensor LH
      • ECM

      • Steering sensor

      • Brake actuator assembly (Skid control ECU)

      • Main body ECU (Multiplex network body ECU)

      Blind spot monitor control is prohibited. Blind spot monitor system warning light on the combination meter turns on.

      U0100

      U0126

      U0129

      U0142

      U0232

      (Blind spot monitor sensor LH)

      Gateway System (Between V bus and sub bus 2)


      • Relays data between V bus and sub bus 2, and monitors ECUs connected to sub bus 2.

      Network gateway ECU

      w/ Pre-crash safety system:


      • Driving support ECU assembly

      • Blind spot monitor sensor LH

      • Seat belt control ECU

      - -

      U0104

      U0233

      U1002

      U1100

      (Network gateway ECU)

      w/o Pre-crash safety system:


      • Lane departure warning camera

      • Blind spot monitor sensor LH

      - -

      U0233

      U023A

      U1002

      (Network gateway ECU)