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CAN COMMUNICATION SYSTEM FAIL-SAFE CHART

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  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 Power management control ECU Control is performed based on default coolant temperature of 80°C (176°F). -

      U0293

      (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 assembly Load control is not performed. -

      U0131

      (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)

      Insolation Correction Control


      • Corrects air conditioning system control operation according to value of solar sensor.

      		 Air conditioning amplifier assembly Main body ECU (multiplex network body ECU) Control is performed based on an insolation value of 0 after communication stop is confirmed. -

      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 Power management control ECU Maintains the latest state (Maintained in normal condition after reset). -

      U0101

      (Air conditioning amplifier 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

      • Combination meter assembly

      • Airbag sensor assembly

      • Speed sensitive automatic lock control does not occur.

      • Shift linked automatic lock 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)

      • ECM

      • Certification ECU (smart key ECU assembly)

      • Interior lights turn off.

      • Mirror foot illumination is turned off.

      • Footwell illumination is turned off.

      • 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 RH (for RHD)

      • Front power seat switch LH (for LHD)

      • Outer mirror control ECU assembly (for driver side)

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

      • Multiplex tilt and telescopic ECU

      • Combination meter assembly

      • Memory function does not operate.

      • Mirrors cannot be adjusted.

      		 -

      U0120

      U0155

      U0199

      U0200

      U0208

      U1115

      (Main body ECU (multiplex network body ECU))

      Electric Fan


      • Controls electric fan in accordance with air conditioning system request

      		 ECM Air conditioning amplifier assembly Electric fan operates fail-safe function. - -
      Power Management ECU (cooperative control with ECM) ECM Power management control ECU Engine is stopped. Displays messages on the multi-information display.  

      PTC Heater


      • Performs idle up in accordance with heating request that includes PTC heater (includes coolant source heat)

      		 ECM Air conditioning amplifier assembly

      • Engine idle speed changes.

      • Heating performance deteriorates.

      • PTC heater does not operate.

      		 - -

      Power Steering Control


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

      		 Power steering ECU assembly

      • Power management control ECU

      • Skid control ECU assembly

      When communication with power management control ECU is interrupted:


      • Power steering assist not provided.

      When communication with skid control ECU assembly 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.

      U0129

      U0293

      (Power steering ECU 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)

      • Combination meter assembly

      • ECM

      		 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

      U0142

      U0155

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

      Memory Function


      • Moves the seat and steering wheel to the recorded positions when smart entry unlock or wireless unlock operation is performed.

      		 Main body ECU (multiplex network body ECU)

      • Main body ECU (multiplex network body ECU)

      • Certification ECU (smart key ECU assembly)

      • Memory system does not operate.

      • Key registration does not operate.

      		 -

      U0142

      (Certification ECU (smart key ECU assembly))

      Power Switch Backlighting Control


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

      		 Certification ECU (smart key ECU assembly) Main body ECU (multiplex network body ECU) Power switch backlighting does not illuminate according to interior lights operation. -

      U0142

      (Certification ECU (smart key ECU assembly))

      Security Indicator Display Function


      • Displays immobiliser and security status.

      		 Certification ECU (smart key ECU assembly) Main body ECU (multiplex network body ECU) Security indicator cannot display security status correctly (security indicator blinks or illuminates when in armed state or alarm sounding state). -

      U0142

      U0293

      (Certification ECU (smart key ECU assembly))
      Vehicle Speed Display Combination meter assembly Skid control ECU assembly

      • 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

      • Needle of tachometer remains at 0 rpm.

      • Drive monitor calculation is stopped.

      		 -

      U0100

      (Combination meter assembly)

      Meter Display


      • Displays vehicle condition and controls indicator lights.

      		 Combination meter assembly

      • ECM

      • Skid control ECU assembly

      • Airbag sensor assembly

      • Main body ECU (multiplex network body ECU)

      • Power steering ECU assembly

      • Headlight leveling ECU assembly

      • Driving support ECU assembly

      • Lane departure warning camera

      		 Lights do not illuminate or lights remain illuminated. Abnormal light operation

      U0100

      U0129

      U0131

      U0142

      U0151

      U0182

      U023A

      U1104

      (Combination meter assembly)

      Buzzer


      • Controls sounding of buzzer for various functions.

      		 Combination meter assembly

      • Main body ECU (multiplex network body ECU)

      • Airbag sensor assembly

      • Skid control ECU assembly

      • Power steering ECU assembly

      • ECM

      		 Buzzer stops sounding or does not sound. None

      U0100

      U0129

      U0131

      U0151

      (Combination meter assembly)

      Destination Identification


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

      		 Combination meter assembly Main body ECU (multiplex network body ECU) None -

      U0142

      (Combination meter assembly)

      Linking-up with Multi-information Display


      • Displays navigation, audio, telephone, etc.

      		 Combination meter assembly Radio receiver assembly None -

      U0163

      (Combination meter assembly)

      Pedestrian Protection Function (Pop-up Hood)


      • Raises the engine hood in event of frontal collision to protect pedestrian.

      		 Airbag sensor assembly

      • Steering sensor

      • Skid control ECU assembly

      • Yaw rate sensor

      		 Airbag ECU assembly prohibits pedestrian protection function and performs calculations accordingly. -

      U0125

      U0126

      U0129

      (Airbag sensor assembly)
      ABS Control Skid control ECU assembly Yaw rate sensor

      • 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 / red (malfunction) illuminates.

      • ABS warning light illuminates.

      • SLIP indicator illuminates.

      • Brake warning light / yellow (minor malfunction) illuminates.

      U0073

      U0123

      U0124

      (Skid control ECU assembly)
      VSC/TRC Control Skid control ECU assembly

      • Yaw rate sensor

      • Steering sensor

      • Power management control ECU

      • 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 / red (malfunction) illuminates.

      • ABS warning light illuminates.

      • SLIP indicator illuminates.

      • Brake warning light / yellow (minor malfunction) illuminates.

      U0073

      U0123

      U0124

      U0126

      U0293

      (Skid control ECU assembly)

      Hill-start Assist Control


      • Maintains brake pressure for 2 seconds when the brake pedal has been depressed further after stopping the vehicle.

      		 Skid control ECU assembly

      • Yaw rate sensor

      • Steering sensor

      • Power management control ECU

      • 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 / red (malfunction) illuminates.

      • ABS warning light illuminates.

      • SLIP indicator illuminates.

      • Brake warning light / yellow (minor malfunction) illuminates.

      U0073

      U0123

      U0124

      U0126

      U0293

      (Skid control ECU assembly)

      Hybrid Regenerative Operation


      • Regenerative cooperative control with the HV system.

      		 Skid control ECU assembly

      • Yaw rate sensor

      • Power management control ECU

      • When control is being performed:

      Control is continued based on the latest value and gradually decreased. Following this, further control is prohibited.


      • When control is not being performed:

      Control will not be started.

      • Brake warning light / red (malfunction) illuminates.

      • ABS warning light illuminates.

      • SLIP indicator illuminates.

      • Brake warning light / yellow (minor malfunction) illuminates.

      U0073

      U0123

      U0124

      U0293

      (Skid control ECU assembly)

      Headlight Leveling Control (Headlight Control)


      • Adjusts headlights vertical aiming according to wheel speed and vehicle pitch angle determined using vehicle height sensor.

      		 Headlight leveling ECU assembly

      • Skid control ECU assembly

      • Main body ECU (multiplex network body ECU)

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

      • Headlight swivel stops with the headlights facing forward.

      		 Displays messages on the multi-information display.

      U0073

      U0129

      U0142

      (Headlight leveling ECU assembly)

      AVS Control


      • Controls the variable damping force according to road and driving conditions.

      		 Absorber control ECU

      • Skid control ECU assembly

      • Steering sensor

      • Yaw rate sensor

      • Power management control ECU

      • Continues to control the damping force.

      • Interrupts damping force control after moving front absorber control actuators and rear absorber control actuators to the 9th step.

      • Controls continue except roll control.

      		 -

      U0101

      U0122

      U0124

      U0126

      U0293

      (Absorber control ECU)

      Air Conditioning Control


      • Controls air conditioning functions such as set temperature adjustment, air outlet selection, etc. by operating LEXUS display audio controller or Remote Touch.

      		 Radio receiver assembly Air conditioning amplifier assembly

      • Air conditioning system indicators turn off.

      • If set temperature is shown on multi-information display or multi-display, set temperature display turns off.

      • Raises the engine hood in event of frontal collision to protect pedestrian.

      		 Displays messages on the multi-information display.

      U0073

      U0164

      (Radio receiver assembly)

      LEXUS Parking Assist System Setting/Notification


      • LEXUS display audio controller or Controls settings for clearance sonar screen notifications which are set by operating Remote Touch, displays sonar status and plays voice warnings.

      		 Radio receiver assembly

      • Power management control ECU

      • Clearance warning ECU assembly

      		 Display updating is stopped. -

      U0073

      U0293

      U1110

      (Radio receiver assembly)

      Fuel Consumption Display


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

      		 Radio receiver assembly

      • ECM

      • Skid control ECU assembly

      • Combination meter assembly

      • Power management control ECU

      When communication with ECM or skid control ECU assembly 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

      U0293

      (Radio receiver assembly)

      HV Energy Flow Display


      • Creates energy flow screen which indicates regeneration status and drive force transmission status.

      		 Radio receiver assembly

      • Power management control ECU

      • ECM

      		 If communication stops while the energy flow screen is displayed, the energy flow display disappears and the latest value is maintained for the SOC (state of charge) level display. -

      U0100

      U0293

      (Radio receiver assembly)

      Parking Assist Monitor Control


      • Display rear view monitor based on steering sensor, vehicle speed and vehicle information.

      		 Radio receiver assembly

      • Power management control ECU

      • Steering sensor

      • Main body ECU (multiplex network body ECU)

      • Power steering ECU assembly

      • Skid control ECU assembly

      • If a communication interruption occurs while predicted path guide lines are displayed, guide lines disappear and a message indicating that guide lines cannot be displayed appears on bottom of screen.

      • If a communication interruption occurs while vehicle is in parallel parking guide mode, a message indicating that guidance is not available appears on bottom of screen.

      • When shift lever is in R, image of area behind vehicle is not displayed (screen is not black).

      		 -

      U0126

      U0129

      U0131

      U0140

      U0293

      (Radio receiver assembly)

      Destination Identification


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

      		 Radio 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

      (Radio receiver assembly)

      Time Stamp Function


      • Matches the relative time from the main body ECU with the absolute time acquired from the GPS.

      		 Radio receiver assembly Main body ECU (multiplex network body ECU) None -

      U0140

      (Radio receiver assembly)

      Tire Pressure Monitoring System


      • Receives information from TPMS ECU to display air pressure, tire location and system status.

      		 Radio receiver assembly Main body ECU (multiplex network body ECU) None -

      U0073

      (Radio receiver assembly)

      Rear View Monitor System


      • Displays images from the rear view camera.

      		 Radio receiver assembly Power management control ECU Screen does not change to the camera screen. -

      U0293

      (Radio receiver assembly)

      Power Tilt and Power Telescopic Steering Column Control


      • Starts steering wheel auto return or auto away based on an power switch on/off signal or equivalent.

      • Memorizes and recalls selected driving position according to memory switch operation.

      • Moves steering wheel to selected position according to manual switch operation on steering column cover.

      		 Multiplex tilt and telescopic ECU

      • Main body ECU (multiplex network body ECU)

      • Front power seat switch LH (for LHD)

      • Front power seat switch RH (for RHD)

      • 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 (for LHD)

      • Front power seat switch RH (for RHD)

      • Main body ECU (multiplex network body ECU)

      • ECM

      • Combination meter assembly

      • Multiplex tilt and telescopic ECU

      		 Controls the seat position based on operation conditions. - -

      Illumination Control


      • Controls illumination of lights based on courtesy switch information and interior light information.

      • 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 foot illumination is turned off. -

      U0142

      (Outer mirror control ECU assembly)
      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)

      • Main body ECU (multiplex network body ECU)

      • Air conditioning amplifier assembly

      		 Mirror heaters do not operate. -

      U0142

      (Outer mirror control ECU assembly)

      Mirror Retract/Return Operation


      • Controls retract/return operation of the outer mirrors based on signals such as mirror switch signal from main body ECU.

      • 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. -

      U0142

      (Outer mirror control ECU assembly)
      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. -

      U0142

      (Outer mirror control ECU assembly)

      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. - -

      Dynamic Radar Cruise Control System


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

      		 Driving support ECU assembly

      • Yaw rate sensor

      • Steering sensor

      • Skid control ECU assembly

      • Power management control ECU

      • Active cruise control is canceled.

      • Fail-safe function operates only during active cruise control.

      • Warning message is displayed or cruise control indicator illuminates in yellow (when cruise control main switch is on).

      • Buzzer sounds (cycle: 0.2 sec., number of times buzzer sounds: 2)

      U0125

      U0126

      U0129

      U0293

      (Driving support ECU assembly)

      Pre-crash System


      • Controls the brakes immediately before a crash.

      		 Driving support ECU assembly

      • Yaw rate sensor

      • Steering sensor

      • Skid control ECU assembly

      • Main body ECU (multiplex network body ECU)

      • Power management control ECU

      		 Control stops.

      • Displays messages on the multi-information display.

      • PCS indicator light flashes.

      U0125

      U0129

      U0142

      U0293

      (Driving support ECU assembly)

      Shift Position Judgment


      • Receives a shift position signal and uses it as a clearance sonar detection operation condition.

      		 Clearance warning ECU assembly Power management control ECU Operation continues at the default shift position of P. -

      U0101

      (Clearance warning ECU assembly)

      LEXUS Parking Assist-Sensor


      • Judges vehicle speed.

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

      U0155

      (Clearance warning ECU assembly)

      Voice Warning Availability Confirmation


      • Uses destination code and steering wheel information for determining availability of voice warning for clearance sonar.

      		 Clearance warning ECU assembly Main body ECU (multiplex network body ECU) Assumes that there is no voice warning. - -

      Lane Departure Alert System


      • Warns when vehicle is deviating from its lane.

      		 Lane departure warning camera

      • Main body ECU (multiplex network body ECU)

      • ECM

      • Combination meter assembly

      • Skid control ECU assembly

      • Yaw rate sensor

      • Driving support ECU assembly

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

      U0101

      U0104

      U0123

      U0129

      U0142

      U0155

      (Lane departure warning camera)

      Automatic High Beam System


      • Controls high beam on/off.

      		 Lane departure warning camera

      • Main body ECU (multiplex network body ECU)

      • Skid control ECU assembly

      • Yaw rate sensor

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

      U0101

      U0123

      U0129

      U0142

      (Lane departure warning camera)

      Blind Spot Monitor Control


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

      		 Blind spot monitor sensor LH

      • Skid control ECU assembly

      • Steering sensor

      • Main body ECU (multiplex network body ECU)

      • Power management control ECU

      		 None Displays messages on the multi-information display.

      U0126

      U0129

      U0142

      U0293

      (Blind spot monitor sensor LH)

      ASC System


      • Outputs simulated engine sounds in accordance with vehicle driving condition.

      		 Stereo component equalizer assembly

      • Main body ECU (multiplex network body ECU)

      • Skid control ECU assembly

      • Power management control ECU

      		 Simulated engine sound output is stopped. -

      U0129

      U0142

      U0293

      (Stereo component equalizer assembly)