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 DTC Detection (Driver Detectable)
      Belt Warning Light Control

      • Main body ECU (multiplex network body ECU)

      • Combination meter assembly

      		 Airbag sensor assembly - -
      Door Lock/Unlock Main body ECU (multiplex network body ECU)

      • Airbag sensor assembly

      • Power management control ECU

      • ECM

      • Combination meter assembly

      • Key linked operation is permitted.

      • Key confinement prevention unlock operation is permitted.

      • Speed linked automatic door lock operation is prohibited.

      • 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)

      • Power management control ECU

      • 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)

      • Power management control ECU

      • Certification ECU (smart key ECU assembly)

      • Combination meter assembly

      • Interior lights are turned off.

      • Mirror foot illumination is turned off.

      • Footwell illumination is turned off.

      • ECO light (blue) and SPORT light (red) illumination cannot be changed between on and off.

      U0101

      U0155

      U0327
      Seat and Mirror Control Main body ECU (multiplex network body ECU)

      • Outer mirror control ECU assembly (driver side)

      • Outer mirror control ECU assembly (front passenger side)

      • Position control ECU and switch assembly

      • Power management control ECU

      • Certification ECU (smart key ECU assembly)

      		 Does not affect vehicle behavior.

      U0199

      U0200

      U0208

      U0327

      U1133
      LED Headlight Warning Control Main body ECU (multiplex network body ECU) Power management control ECU LED headlight warning control do not operate. U0293

      Destination Identification for the LEXUS Parking Assist-sensor System

      (Identifies the market that the vehicle was produced for and controls audio data output.)

      		 Main body ECU (multiplex network body ECU) - Continues the operation during control before the communication interruption. U0142

      Seat Memory Switch Signal Forwarding

      (Sends switch operation status via MS-CAN.)

      		 Main body ECU (multiplex network body ECU)

      • Outer mirror control ECU assembly (driver side)

      • 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 (the market that vehicle was produced for) and steering wheel position information (LHD/RHD) cannot be determined.


      • Control is performed based on default destination when undetermined.

      • 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. -

      Vehicle Customization Function

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

      		 Radio receiver assembly

      • Air conditioning amplifier assembly

      • Main body ECU (multiplex network body ECU)

      • Certification ECU (smart key ECU assembly)

      • Customization via multi-display is not possible, but customization via main body ECU is possible.

      • When an application that uses 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.

      U0073

      B15F5

      B15F6

      B15F7

      Smart Camera Function

      (Displays the image from the rear television camera assembly with the predicted path guide lines, vehicle width extension guide lines and distance guide lines overlaid when reversing.)

      		 Radio receiver assembly

      • Power management control ECU

      • Rear television camera assembly

      		 Camera diagnosis screen and camera screen are turned off. -

      Air Conditioning Control

      (Controls air conditioning functions shown on the multi-display.)

      		 Radio receiver assembly Air conditioning amplifier assembly

      • Air conditioning connection confirmation screen is displayed.

      • Air conditioning cannot be operated.

      U0073

      U0164
      LEXUS Parking Assist-sensor System Setting/Notification Radio receiver assembly

      • Clearance warning ECU assembly

      • Power management control ECU

      • Display is not updated.

      • Setting screen is not displayed.

      U0073

      U0100

      U1110

      Multi-display

      (HV energy flow display)

      		 Radio receiver assembly Power management control ECU Display is not updated. U0293

      Navigation Destination Identification

      (Displays language and time zone selection function.)

      		 Radio receiver assembly Main body ECU (multiplex network body ECU) Determined using information from before the communication error. U0140

      Fuel Consumption Display

      (Displays graph of fuel consumption per minute and history of total fuel consumption.)

      		 Radio receiver assembly

      • Power management control ECU

      • Combination meter assembly

      • ECM

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

      • Display is not updated.

      • Updated section average fuel consumption graph and numeric part of the drivable distance on the Eco navigation (eco drive) display are turned off.

      U0100

      U0129

      U0155

      U0293
      Back Guide Monitor Radio receiver assembly (for navigation receiver type)

      • Power management control ECU

      • Main body ECU (multiplex network body ECU)

      • Steering angle sensor (spiral cable with sensor sub-assembly)

      		 Estimated guide lines are not displayed.

      U0100

      U0126

      U0140

      U0293

      Memory Call Function

      (Recalls seat position memory settings based on smart key information when door is unlocked.)

      		 Main body ECU (multiplex network body ECU)

      • Outer mirror control ECU assembly (driver side)

      • Outer mirror control ECU assembly (front passenger side)

      • Position control ECU and switch assembly

      • Certification ECU (smart key ECU assembly)

      • Combination meter assembly

      		 Seat position cannot be memorized or recalled. U0142
      LEXUS Parking Assist-sensor System Detection Operation Clearance warning ECU assembly

      • Power management control ECU

      • Combination meter assembly

      		 Obstacle detection is stopped.

      U0101

      U0155

      Parking Assist Monitor

      (Monitors the shift position signal, steering angle signal and vehicle speed, and displays the predicted path guide lines on the screen based on the steering angle when reversing.)

      		 Rear television camera assembly

      • Power management control ECU

      • Steering angle sensor (spiral cable with sensor sub-assembly)

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

      • Main body ECU (multiplex network body ECU)

      • Clearance warning ECU assembly

      • Radio receiver assembly

      • Parking assist monitor function is prohibited.

      • Predicted path guide lines are not displayed.

      U0100

      U0126

      U0129

      U0140

      U0163

      U0293

      U1110
      Mirror Surface Adjustment

      • Outer mirror control ECU assembly (driver side)

      • 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

      • Outer mirror control ECU assembly (driver side)

      • 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

      • Outer mirror control ECU assembly (driver side)

      • 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

      • Outer mirror control ECU assembly (driver side)

      • Outer mirror control ECU assembly (front passenger side)

      		 Main body ECU (multiplex network body ECU) Mirrors cannot be retracted or returned. -
      Mirror Heaters

      • Outer mirror control ECU assembly (driver side)

      • Outer mirror control ECU assembly (front passenger side)

      • Main body ECU (multiplex network body ECU)

      • Air conditioning amplifier assembly

      		 Mirror heaters do not operate. U0142
      Mirror Foot Illumination

      • Outer mirror control ECU assembly (driver side)

      • Outer mirror control ECU assembly (front passenger side)

      		 Main body ECU (multiplex network body ECU) Mirror foot illumination does not operate. -

      Seat Position Memory System

      (Controls the seat position based on operation conditions.)

      		 Position control ECU and switch assembly

      • Power management control ECU

      • ECM

      • Main body ECU (multiplex network body ECU)

      • Combination meter assembly

      		 Position does not change or cannot be recalled. -

      Hybrid Regenerative Operation


      • Regenerative cooperative control with the HV system.

      		 Skid control ECU (brake booster with master cylinder assembly)

      • Certification ECU (smart key ECU assembly)

      • Power management control ECU

      • Airbag sensor assembly

      • During control: HV cooperative control is continued based on the latest value and gradually decreased. After this, HV cooperative control is prohibited.

      • Not during control: HV cooperative control does not start.

      U0073

      U0120

      U0123

      U0124

      U0293

      (Warning and indicator lights come on.)

      • ABS

      • TRC

      • VSC

      • Hill-start Assist Control

      		 Skid control ECU (brake booster with master cylinder assembly)

      • Power management control ECU

      • Steering angle sensor (spiral cable with sensor sub-assembly)

      • Yaw rate and acceleration sensor

      • During control: When control (vehicle behavior stabilization) is complete, further control is prohibited.

      • Not during control: Control is prohibited.

      U0073

      U0123

      U0124

      U0126

      U0293

      (Warning and indicator lights come on.)
      HV Driving Control Power management control ECU ECM Vehicle drives using only the motor (Engine is not used).

      U0100

      (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 sensor 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. U0164
      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 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).)

      U0129

      (Indicator light comes on.)

      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

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

      • Steering angle sensor (spiral cable with sensor sub-assembly)

      • Yaw rate and acceleration sensor

      		 Steering force differs between right and left or is uneven.

      U0129

      (Indicator light comes on.)
      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 sensor assembly - -
      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

      • Main body ECU (multiplex network body ECU)

      • Transmission control ECU assembly

      • 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

      • Airbag sensor assembly

      • Main body ECU (multiplex network body ECU)

      • Clearance warning ECU assembly

      • Driving support ECU assembly

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

      • Power management control ECU

      • Power steering ECU assembly

      • ECM

      • Position control ECU and switch assembly

      		 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

      • Main body ECU (multiplex network body ECU)

      • Driving support ECU assembly

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

      • Power management control ECU

      • Power steering ECU assembly

      • 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.


      • READY buzzer

      • EPS buzzer

      • Certification completion notification/smart key single buzzer

      • Radar cruise low speed cancel buzzer

      • Sport shift reject buzzer

      • Shift operation reject buzzer

      • 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.


      • READY buzzer

      • Reverse buzzer

      • Light reminder buzzer

      • Seat belt buzzer

      • Warning when driving with the parking brake unreleased

      • Warning when driving with a door ajar

      • Smart key intermittent buzzer

      • Brake system buzzer

      • Smart key continuous buzzer

      • NDB warning buzzer (P position request buzzer)

      • HV battery low voltage warning buzzer

      • Speed warning buzzer (only for Middle East)

      • Slide roof warning buzzer

      • Accelerator depressed with neutral (N) selected

      U0129

      U0131

      U0142
      Multi-display Combination meter assembly

      • Radio receiver assembly

      • Main body ECU (multiplex network body ECU)

      • Clearance warning ECU assembly

      • Driving support ECU assembly

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

      • Power management control ECU

      • Power steering ECU assembly

      • ECM

      • Certification ECU (smart key ECU assembly)

      • Position control ECU and switch assembly

      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.


      • HV system warning

      • Cruise warning, Automatic cruise control (ACC) display state

      • PCS warning

      • Door ajar warning

      • Smart system/power management control warning

      • Parking brake unreleased warning

      • Sliding roof warning

      • EV MODE indicator/warning

      • Intrusion sensor operation display

      • 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

      • Air conditioning amplifier assembly

      • Main body ECU (multiplex network body ECU)

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

      • Power management control ECU

      • ECM

      • Clearance warning ECU assembly

      • Transmission control ECU assembly

      • Energy monitor is not displayed on the multi-information display.

      • Ambient temperature E°C (E°F) is displayed.

      • 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

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

      • 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

      • Airbag sensor assembly

      • Main body ECU (multiplex network body ECU)

      • Driving support ECU assembly

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

      • Power management control ECU

      • Power steering ECU assembly

      • Position control ECU and switch assembly

      		 - -
      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. -

      Electronic Shift Lever System

      (Displays error messages on the multi-information display.)

      		 Transmission control ECU assembly Combination meter assembly Displays messages on the multi-information display. U0103

      Dynamic Radar Cruise Control System


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

      		 Driving support ECU assembly

      • Yaw rate and acceleration sensor

      • Steering angle sensor (spiral cable with sensor sub-assembly)

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

      • Millimeter wave radar sensor assembly

      • Forward recognition camera

      • Power management control ECU

      		 Control stops.

      U0125

      U0126

      U0129

      U0235

      U0293

      U1104


      • (Displays messages on the multi-information display.)

      • (Buzzer sounds.)

      Pre-collision System


      • Performs pre-collision alarm control, pre-collision brake assist control and pre-collision brake control when an obstruction is detected.

      		 Driving support ECU assembly

      • Yaw rate and acceleration sensor

      • Steering angle sensor (spiral cable with sensor sub-assembly)

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

      • Millimeter wave radar sensor assembly

      • Forward recognition camera

      • Power management control ECU

      • Driving support ECU assembly

      		 Control stops.

      U0125

      U0126

      U0129

      U0235

      U023A

      U0293

      U1002

      U1104


      • (PCS indicator light flashes.)

      • (Displays messages on the multi-information display.)

      Pre-collision System


      • Detects vehicles and pedestrians and applies the brakes automatically if necessary.

      		 Forward recognition camera

      • Yaw rate and acceleration sensor

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

      • Main body ECU (multiplex network body ECU)

      • Millimeter wave radar sensor assembly

      • Power management control ECU

      • Driving support ECU assembly

      		 Detection processing is reset and signals indicating that the forward recognition camera is not detecting objects are sent to the driving support ECU assembly.

      U0123

      U0129

      U0142

      U0235

      U0293

      U1104


      • (PCS indicator light flashes.)

      • (Displays messages on the multi-information display.)

      LDA/SWS System

      (Recognizes the lane markers of the lane the vehicle is in using the forward recognition camera and performs the following operations based on the vehicle condition and information captured by the forward recognition camera.)


      • If the system judges that the vehicle may deviate from the lane it is in, the system performs steering assist to help the driver correct the path of the vehicle.

      • If the system judges that the vehicle deviated from the lane it is in, the system sounds a buzzer to inform the driver of lane departure.

      • If the system judges unsteady driving, the system informs the driver to stop and take a rest.

      		 Forward recognition camera

      • Power management control ECU

      • Yaw rate and acceleration sensor

      • Steering angle sensor (spiral cable with sensor sub-assembly)

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

      • Power steering ECU assembly

      • Main body ECU (multiplex network body ECU)

      • Combination meter assembly

      • Millimeter wave radar sensor assembly

      • Driving support ECU assembly

      		 Control stops.

      U0101

      U0123

      U0126

      U0129

      U0131

      U0142

      U0155

      U0235

      U023A

      U0293

      U1104


      • (Displays messages on the multi-information display.)

      • (Lane departure alert indicator light (yellow) illuminates.)

      Automatic High Beam System


      • Controls the high beam automatically when the forward recognition camera detects a preceding vehicle or an oncoming vehicle.

      		 Forward recognition camera

      • ECM

      • Power management control ECU

      • Yaw rate and acceleration sensor

      • Main body ECU (multiplex network body ECU)

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

      • Millimeter wave radar sensor assembly

      		 Performs control based on the signals received before the malfunction occurred.

      U0101

      U0123

      U0126

      U0129

      U0235

      U0293

      (Displays messages on the multi-information display.)

      Road Sign Assist Function


      • Identifies road signs while driving and displays them on the multi-information display.

      		 Forward recognition camera

      • Power management control ECU

      • Yaw rate and acceleration sensor

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

      • Main body ECU (multiplex network body ECU)

      • Combination meter assembly

      		 Road sign assist function is canceled.

      U0101

      U0123

      U0129

      U0142

      U0155

      U0293


      • (Suspends display of road signs on the multi-information display.)

      • (Displays messages on the multi-information display)