CAN COMMUNICATION SYSTEM > FAIL-SAFE CHART

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FAIL-SAFE FUNCTION

  1. When communication fails in any of the CAN bus lines (communication wires), 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
    		DTC Detection (Driver Detectable)
    Vehicle customization function
    (Allows changing of operation and control conditions for vehicle functions via multi-display operation)
    		Navigation ECU (Navigation computer sub-assembly) w/ Navigation system (for HDD)
    1. Air conditioning amplifier assembly
    2. Main body ECU (Multiplex network body ECU)
    3. Outer mirror control ECU assembly (Driver side)
    4. Certification ECU (Smart key ECU assembly)
    5. Combination meter assembly
    1. Customization via multi-display is not possible, but customization via main body ECU is possible.
    2. When an application that uses remote communication is activated (customization/remote diagnosis), the process will be performed regardless of meter ECU remote communication permit/prohibit state.
    		U0073
    Belt warning light control
    1. Main body ECU (Multiplex network body ECU)
    2. Combination meter assembly
    		Airbag ECU assembly
    		Driver and front passenger seat belt warning lights do not operate.
    		-
    Door lock/unlock
    		Main body ECU (Multiplex network body ECU)
    1. Airbag ECU assembly
    2. Power management control ECU
    3. ECM
    4. Combination meter assembly
    1. Key linked operation is permitted.
    2. Key confinement prevention unlock operation is permitted.
    3. Speed linked automatic door lock operation is prohibited.
    4. Shift linked automatic lock/unlock operation is prohibited.
    		U0100
    U0101
    U0151
    U0155
    U0293
    U1133
    Alarm
    (Sounds the alarm)
    		Main body ECU (Multiplex network body ECU)
    1. Power management control ECU
    2. ECM
    		Alarm cannot be sounded.
    		-
    Back door open control
    		Main body ECU (Multiplex network body ECU)
    		Combination meter assembly
    		Back door open control is prohibited.
    		U0155
    Illumination control
    		Main body ECU (Multiplex network body ECU)
    1. Power management control ECU
    2. Certification ECU (Smart key ECU assembly)
    1. Interior lights are turned off.
    2. Mirror foot illumination is turned off.
    3. Footwell illumination is turned off.
    		U0101
    U0327
    Seat and mirror control
    		Main body ECU (Multiplex network body ECU)
    1. Outer mirror control ECU assembly (Driver side)
    2. Outer mirror control ECU assembly (Front passenger side)
    3. Position control ECU and switch assembly
    4. Power management control ECU
    5. ECM
    6. Certification ECU (Smart key ECU assembly)
    		Does not affect vehicle behavior
    		-
    LED headlight warning control
    		Main body ECU (Multiplex network body ECU)
    		Power management control ECU
    		LED headlights do not operate.
    		U0293
    Destination identification for the LEXUS parking assist-sensor system
    (Identifies the market the vehicle was produced for and controls audio data output)
    		Main body ECU (Multiplex network body ECU)
    		-
    		Continues the operation being performed before the communication interruption.
    		U0142
    Seat memory switch signal forwarding
    (Sends switch operation status via MS-CAN)
    		Main body ECU (Multiplex network body ECU)
    1. Outer mirror control ECU assembly (Driver side)
    2. Outer mirror control ECU assembly (Front passenger side)
    		Seat position memory settings cannot be memorized or recalled
    		-
    Electric water pump (engine water pump) control
    (Electric water pump operation control when the engine is stopped)
    		Air conditioning amplifier assembly
    		ECM
    		Performs control as if the engine is stopped (0 rpm).
    		-
    Air conditioning control
    (In-cabin air conditioning control)
    		Air conditioning amplifier assembly
    		ECM
    		Temperature adjustment function effectiveness declines.
    		-
    Ambient temperature correction control
    (Correction and display of ambient temperature)
    		Air conditioning amplifier assembly
    		Combination meter assembly
    		Ambient temperature correction effectiveness declines.
    		-
    Electric compressor control
    		Air conditioning amplifier assembly
    		Combination meter assembly
    		Air conditioning effectiveness declines.
    		-
    Air conditioning control changes
    		Air conditioning amplifier assembly
    		Main body ECU (Multiplex network body ECU)
    		Accurate destination (market that vehicle was produced for) and steering wheel position information (LHD/RHD) cannot be determined.
    1. Control is performed based on default destination when undetermined.
    2. Air conditioning control function effectiveness declines.
    		-
    Electric compressor protection control
    		Air conditioning amplifier assembly
    		Power management control ECU
    		Air conditioning cooling function does not operate.
    		-
    Air conditioning control
    (Controls air conditioning functions shown on the multi-display)
    		Navigation ECU (Display and navigation module display) w/ Navigation system (for DVD)
    Navigation ECU (Navigation computer sub-assembly) w/ Navigation system (for HDD)
    		Air conditioning amplifier assembly
    1. Air conditioning connection confirmation screen is displayed.
    2. Air conditioning cannot be operated.
    		U0073
    U0164
    LEXUS parking assist-sensor system setting/notification
    		Navigation ECU (Display and navigation module display) w/ Navigation system (for DVD)
    Navigation ECU (Navigation computer sub-assembly) w/ Navigation system (for HDD)
    1. Clearance Warning ECU assembly
    2. Power management control ECU
    3. Skid control ECU (Brake booster with master cylinder assembly)
    1. Display is not updated.
    2. Setting screen is not displayed.
    		U0073
    U1110
    Multi-display
    (HV energy flow display)
    		Navigation ECU (Display and navigation module display) w/ Navigation system (for DVD)
    Navigation ECU (Navigation computer sub-assembly) w/ Navigation system (for HDD)
    		Power management control ECU
    		Display is not updated.
    		U0073
    U0293
    Navigation destination identification
    (Display language and time zone selection function)
    		Navigation ECU (Display and navigation module display) w/ Navigation system (for DVD)
    Navigation ECU (Navigation computer sub-assembly) w/ Navigation system (for HDD)
    		Main body ECU (Multiplex network body ECU)
    		Determined using information from before the communication error.
    		U0073
    Memory call function
    (Recalls Seat position memory settings based on smart key information when door is unlocked)
    		Main body ECU (Multiplex network body ECU)
    1. Outer mirror control ECU assembly (Driver side)
    2. Outer mirror control ECU assembly (Front passenger side)
    3. Position control ECU and switch assembly
    4. Certification ECU (Smart key ECU assembly)
    5. Combination meter assembly
    		Seat position cannot be memorized or recalled.
    		U0142
    Back guide monitor
    		Parking assist ECU
    1. Main body ECU (Multiplex network body ECU)
    2. Clearance Warning ECU assembly
    3. Steering angle sensor (Spiral cable with sensor sub-assembly)
    1. Estimated guide lines are not displayed.
    2. Cooperative control with the LEXUS parking assist-sensor system is stopped.
    3. Guide lines cannot be adjusted.
    		U0126
    U0140
    U1110
    LEXUS parking assist-sensor system detection operation
    		Clearance Warning ECU assembly
    1. Power management control ECU
    2. Combination meter assembly
    		Obstacle detection is stopped.
    		U0101
    U0155
    Mirror surface adjustment
    1. Outer mirror control ECU assembly (Driver side)
    2. Outer mirror control ECU assembly (Front passenger side)
    		Main body ECU (Multiplex network body ECU)
    		Mirror surface position adjustment is not possible.
    		U0142
    Mirror surface position memory and recall
    1. Outer mirror control ECU assembly (Driver side)
    2. Outer mirror control ECU assembly (Front passenger side)
    		Main body ECU (Multiplex network body ECU)
    		Mirror surface position cannot be memorized or recalled.
    		-
    Reverse-shift linked door mirror operation
    1. Outer mirror control ECU assembly (Driver side)
    2. Outer mirror control ECU assembly (Front passenger side)
    		Main body ECU (Multiplex network body ECU)
    		Reverse-shift linked operation is unavailable.
    		-
    Mirror retract/return operation
    1. Outer mirror control ECU assembly (Driver side)
    2. Outer mirror control ECU assembly (Front passenger side)
    		Main body ECU (Multiplex network body ECU)
    		Mirrors cannot be retracted or returned.
    		-
    Mirror heaters
    1. Outer mirror control ECU assembly (Driver side)
    2. Outer mirror control ECU assembly (Front passenger side)
    1. Main body ECU (Multiplex network body ECU)
    2. Air conditioning amplifier assembly
    		Mirror heaters do not operate.
    		U0142
    Mirror foot illumination
    1. Outer mirror control ECU assembly (Driver side)
    2. Outer mirror control ECU assembly (Front passenger side)
    		Main body ECU (Multiplex network body ECU)
    		Mirror foot illumination does not operate.
    		-
    Pre-crash control
    (Brake and seat belt operation when a collision is detected.)
    		Driving support ECU assembly
    1. Power management control ECU
    2. ECM
    3. Skid control ECU (Brake booster with master cylinder assembly)
    4. Steering angle sensor (Spiral cable with sensor sub-assembly)
    5. Yaw rate and acceleration sensor
    6. Seat belt control ECU
    7. Main body ECU (Multiplex network body ECU)
    		Pre-crash control is prohibited.
    		U0122
    U0123
    U0126
    U0293
    U1100
    U1104
    Indicator illuminates
    Seat belt control ECU
    1. Skid control ECU (Brake booster with master cylinder assembly)
    2. Airbag ECU assembly
    3. Driving support ECU assembly
    4. Main body ECU (Multiplex network body ECU)
    		Pre-crash control is prohibited.
    		U0122
    U0140
    U0151
    U1104
    Indicator illuminates
    Radar cruise control
    (Vehicle to vehicle distance control)
    		Driving support ECU assembly
    1. Power management control ECU
    2. ECM
    3. Skid control ECU (Brake booster with master cylinder assembly)
    4. Steering angle sensor (Spiral cable with sensor sub-assembly)
    5. Yaw rate and acceleration sensor
    6. Main body ECU (Multiplex network body ECU)
    7. Combination meter assembly
    		Vehicle to vehicle distance control is prohibited.
    		U0122
    U0123
    U0126
    U0293
    U1104
    Indicator illuminates
    Seat position memory system
    (Controls the seat position based on operation conditions)
    		Position control ECU and switch assembly
    1. Power management control ECU
    2. ECM
    3. Main body ECU (Multiplex network body ECU)
    4. Combination meter assembly
    		Position does not change or cannot be recalled.
    		-
    Regenerative braking
    		Skid control ECU (Brake booster with master cylinder assembly)
    		Power management control ECU
    		Regenerative braking is stopped.
    		U0073
    U0123
    U0124
    U0293
    Warning and indicator lights come on
    1. ABS
    2. TRC
    3. VSC
    4. Hill-start assist control
    		Skid control ECU (Brake booster with master cylinder assembly)
    1. Power management control ECU
    2. Steering angle sensor (Spiral cable with sensor sub-assembly)
    3. Yaw rate and acceleration sensor
    		Control is stopped.
    		U0073
    U0123
    U0124
    U0126
    U0293
    Warning and indicator lights come on
    VDIM cooperative control
    		Skid control ECU (Brake booster with master cylinder assembly)
    		Power steering ECU assembly
    		Control is stopped.
    		U0129
    Indicator illuminates
    HV driving control
    		Power management control ECU
    		ECM
    		Vehicle drives using only the motor (Engine is not used)
    		U0100
    U0293
    Warning light comes on
    Regenerative operation
    		Power management control ECU
    		Skid control ECU (Brake booster with master cylinder assembly)
    		Regeneration is prohibited.
    		U0129
    Warning light comes on
    Collision judgment
    		Power management control ECU
    		Airbag ECU assembly
    		Does not affect vehicle behavior
    		U0151
    Warning light comes on
    Air conditioning inverter control
    		Power management control ECU
    		Air conditioning amplifier assembly
    		Air conditioning cooling operation is stopped.
    		-
    HV system power processing
    		Power management control ECU
    		-
    		Power switch cannot be turned off.
    (Power switch can be turned off when park (P) is detected.)
    		U1107
    Warning light comes on
    Electric power steering control
    (Changes assist power based on vehicle speed)
    		Power steering ECU assembly
    		Skid control ECU (Brake booster with master cylinder assembly)
    		Continues to perform control based on a default speed of 100 km/h (62 mile) because vehicle speed is unrecognizable.
    (Steering wheel feels heavy when the vehicle speed is below 100 km/h and feels light at speeds above 100 km/h (62 mile).)
    		U0129
    Indicator illuminates
    Electric power steering assist start judgment
    (Judges Ready status and permits assist)
    		Power steering ECU assembly
    		Power management control ECU
    		Permits assist after the engine starts idling
    (Assist is not performed before engine starts)
    		U0293
    Warning and indicator lights come on
    Assist map selection
    (Selects proper assist map according to destination, engine type, etc.)
    		Power steering ECU assembly
    		Power management control ECU
    		Default map is used to assist because proper assist map cannot be selected.
    (Steering feel may be different.)
    		-
    Steering initialization and zero point learning
    		Power steering ECU assembly
    1. Skid control ECU (Brake booster with master cylinder assembly)
    2. Steering angle sensor (Spiral cable with sensor sub-assembly)
    3. Yaw rate and acceleration sensor
    		Steering force differs between right and left or is uneven
    		U0129
    Indicator illuminates
    Power switch illumination control
    		Certification ECU (Smart key ECU assembly)
    		Main body ECU (Multiplex network body ECU)
    		Illumination does not operate
    		U0142
    Airbag warning light control
    		Combination meter assembly
    		Airbag ECU assembly
    		Fuel cut function in the event of a collision is stopped.
    		-
    Power steering warning light illumination
    		Combination meter assembly
    		Power steering ECU assembly
    		Warning light turns off when communication is interrupted.
    		-
    Coolant temperature display
    		Combination meter assembly
    		ECM
    		Display is turned off.
    		-
    Vehicle speed display
    		Combination meter assembly
    		Skid control ECU (Brake booster with master cylinder assembly)
    		Vehicle speed display remains at 0 km/h (0 mph).
    		U0100
    U0129
    Odometer/Trip meter
    		Combination meter assembly
    		Skid control ECU (Brake booster with master cylinder assembly)
    		Display is not updated.
    		U0100
    U0129
    HV system indicator
    		Combination meter assembly
    		Power management control ECU
    		The needle of the indicator will remain at the bottom.
    		-
    Shift position indicator display
    		Combination meter assembly
    1. Main body ECU (Multiplex network body ECU)
    2. Transmission control ECU assembly
    3. Power management control ECU
    		Backlighting only for the letters, arrows and home position of the shift position indicator illuminate.
    		-
    Meter display
    (Displays vehicle condition and controls indicator lights)
    		Combination meter assembly
    1. Airbag ECU assembly
    2. Main body ECU (Multiplex network body ECU)
    3. Clearance warning ECU assembly
    4. Driving support ECU assembly
    5. Skid control ECU (Brake booster with master cylinder assembly)
    6. Power management control ECU
    7. Power steering ECU assembly
    8. ECM
    9. Seat belt control ECU
    		Lights do not illuminate or lights remain illuminated
    		U0100
    U0129
    U0131
    U0142
    U0151
    (Abnormal light operation or light does not illuminate)
    Buzzer
    (Controls sounding of buzzer for various functions)
    		Combination meter assembly
    1. Main body ECU (Multiplex network body ECU)
    2. Driving support ECU assembly
    3. Skid control ECU (Brake booster with master cylinder assembly)
    4. Power management control ECU
    5. Power steering ECU assembly
    6. Certification ECU (Smart key ECU assembly)
    		The sounding of the buzzer for the following items remains unchanged when the power switch is on (IG) and does not sound when the power switch is off.
    1. READY buzzer
    2. EPS buzzer
    3. Certification completion notification/smart key single buzzer
    4. Radar cruise low speed cancel buzzer
    5. Sport shift reject buzzer
    6. Shift operation reject buzzer
    7. EV reject buzzer
    The sounding of the buzzer for the following items stops when the power switch is on (IG), and stops sounding/does not sound when the power switch is off.
    1. READY buzzer
    2. Reverse buzzer
    3. Light reminder buzzer
    4. Seatbelt buzzer
    5. Warning when driving with the parking brake unreleased
    6. Warning when driving with a door ajar
    7. Smart key intermittent buzzer
    8. Brake system buzzer
    9. Smart key continuous buzzer
    10. NDB warning buzzer (P position request buzzer)
    11. HV battery low voltage warning buzzer
    12. Speed warning buzzer (only for Middle East)
    13. Slide roof warning buzzer
    14. Accelerator depressed with neutral (N) selected
    		U0129
    U0131
    U0142
    Multi-display
    		Combination meter assembly
    1. Navigation ECU (Display and navigation module display) (for DVD navigation system)
    2. Navigation ECU (Navigation computer sub-assembly) (for HDD navigation system)
    3. Main body ECU (Multiplex network body ECU)
    4. Clearance warning ECU assembly
    5. Driving support ECU assembly
    6. Skid control ECU (Brake booster with master cylinder assembly)
    7. Power management control ECU
    8. Power steering ECU assembly
    9. ECM
    10. Certification ECU (Smart key ECU assembly)
    11. Seat belt control ECU
    		LEXUS parking assist-sensor system is not displayed
    LEXUS parking assist-sensor system status is not displayed.
    Light reminder warning is turned off.
    Speed warning (only for Middle East)
    The following warnings are controlled based on the latest signal state until the power switch is turned off.
    1. HV system warning
    2. Cruise warning, Automatic cruise control (ACC) display state
    3. PCS warning
    4. Door ajar warning
    5. Smart system/power management control warning
    6. Parking brake unreleased warning
    7. Sliding roof warning
    8. EV MODE indicator/warning
    9. Intrusion sensor operation display
    10. LED headlight warning
    		U0100
    U0129
    U0131
    U0142
    Multi-information display (Cruise information display)
    (Energy monitor / Mileage & Average fuel economy / Instantaneous fuel economy & Average fuel economy after refueling / Drivable mileage / Average vehicle speed / Ambient temperature)
    		Combination meter assembly
    1. Air conditioning amplifier assembly
    2. Main body ECU (Multiplex network body ECU)
    3. Skid control ECU (Brake booster with master cylinder assembly)
    4. Power management control ECU
    5. ECM
    6. Clearance warning ECU assembly
    7. Transmission control ECU assembly
    1. Energy monitor is not displayed on the multi-information display.
    2. Ambient temperature E°C (E°F) is displayed.
    3. Displays for other items are not updated.
    		-
    ECO light (blue) and SPORT light (red) display
    (Controls ECO light (blue) based on ECO zone display state and SPORT light (red) based on SPORT mode signal)
    		Combination meter assembly
    		Power management control ECU
    		ECO (blue) and SPORT (red) are turned off.
    		-
    Tachometer
    (Displays engine speed)
    		Combination meter assembly
    		Power management control ECU
    		The needle points at 0 rpm.
    		-
    FUEL gauge
    		Combination meter assembly
    1. Skid control ECU (Brake booster with master cylinder assembly)
    2. Power management control ECU
    		-
    		-
    Display automatic dimming control
    (Brightness of displays changes between bright areas and dark areas according to light control sensor)
    		Combination meter assembly
    		Main body ECU (Multiplex network body ECU)
    		Maintains the latest state.
    		U0155
    Diagnostic system
    Receives signals from ECUs with DTCs and controls the operation of warning indicators or messages based on the signals received.
    (Receives trip counter and time counter signals, and stores each value when the system is malfunctioning)
    		Combination meter assembly
    1. Airbag ECU assembly
    2. Main body ECU (Multiplex network body ECU)
    3. Driving support ECU assembly
    4. Skid control ECU (Brake booster with master cylinder assembly)
    5. Power management control ECU
    6. Power steering ECU assembly
    7. Seat belt control ECU
    		-
    		-
    P position switch indicator light display function
    		Transmission control ECU assembly
    		Main body ECU (Multiplex network body ECU)
    		-
    		U0146
    (Indicator goes off)
    P control DTC detection
    (Used as a malfunction detection condition for DTC C2309, C2315 and U0146)
    		Transmission control ECU assembly
    		Main body ECU (Multiplex network body ECU)
    		-
    		U0146
    P control CPU sleep control
    		Transmission control ECU assembly
    		Main body ECU (Multiplex network body ECU)
    		Ignition off state cannot be judged using CAN data.
    		U0146
    P position switch indicator light dimmer control
    		Transmission control ECU assembly
    		Main body ECU (Multiplex network body ECU)
    		-
    		U0146
    SPORT mode change control
    		Power management control ECU
    		Power steering ECU assembly
    		SPORT mode change control does not operate.
    		-
    Idle map
    		Power management control ECU
    		Power steering ECU assembly
    		Idle up is not performed.
    		-