Fail-Safe Chart
- FAIL-SAFE FUNCTION
- When communication fails in any of the main wires (communication lines) due to a short circuit or other causes, the fail-safe function, which is specified for each system, operates to prevent the system from malfunctioning.
- The table below shows the effects on each system when communication is impossible. For further details, refer to each system.
FAIL-SAFE CHART
| Function (Function Description) | Control Master | System Related | Control Actuator | Fail-safe Operation | Driver Detectable |
|---|---|---|---|---|---|
| Lighting (Dimmer switch is in AUTO position) | Main Body ECU (MS bus) |
|
|
Dimmer switch AUTO position is maintained | None |
| Lighting (Taillight, headlight, high beam light, front fog light, rear fog light, cornering light, license plate light, side marker light) | Main Body ECU (MS bus) |
|
|
Light turns OFF | None |
| Back-up light control | ECM (V bus) | ECM (V bus) | Rear Junction Block ECU | When back-up light is on, it turns OFF | None |
| DRL control | Main Body ECU (MS bus) | Main Body ECU (MS bus) | Front Controller |
|
None |
| Headlight cleaner alternative output | Main Body ECU (MS bus) |
|
- | Output OFF | None |
Illumination control
|
Main Body ECU (MS bus) |
|
|
Illumination (room light) control does not operate (conditions below apply)
|
None |
| Door lock/unlock | Main Body ECU (MS bus) |
|
|
IDT, DRD, DRP, DRR, DRL and CBG communication stop: Wireless, smart, remote, key-linked / LEXUS link, and other systems' various door lock control operations are not possible | None |
| Door lock (Double lock control) | Main Body ECU (MS bus) |
|
|
Double lock does not operate | None |
| Entry lock/unlock | Certification ECU |
|
|
Entry lock/unlock not possible | None |
| Entry luggage compartment | Certification ECU |
|
|
Entry luggage compartment lock/ unlock not possible | None |
| Warning function | Certification ECU |
|
- | Warning buzzer not possible | None |
| Alarm | Certification ECU |
|
Front Controller | Alarm not possible | None |
| Immobiliser | Certification ECU |
|
- | Immobiliser operation not possible | None |
| Security | Certification ECU |
|
- | Security set not possible | None |
| Power window (key-linked power window control) | Main Body ECU (MS bus) | Front Multiplex Network Door ECU LH | - | During key-linked power window operation, after fail-safe time elapses, power window operation stops | None |
| Door closer |
|
|
|
Door closer function stops (if door closer is operating, operation continues until it is finished, then function stops) | None |
| Trunk operation (without PTL) | Rear Junction Block ECU |
|
Rear Junction Block ECU | Luggage compartment door closer operation is not possible (only operation with mechanical key is possible) | None |
| Power trunk lid open/ close (electric) | Power Trunk Lid Control ECU |
|
Power Trunk Lid Control ECU | Power trunk lid operation not possible (only operation with mechanical key is possible) | None |
| Mirror surface memory/call |
|
|
|
Memory and call not possible | None |
| Mirror surface alignment |
|
Outer Mirror Switch |
|
Adjustment not possible | None |
| Mirror retract/Return |
|
Outer Mirror Switch |
|
Retract and return impossible | None |
| Mirror reverse-linked |
|
|
|
Reverse-linked operation impossible | None |
| Mirror heater |
|
|
|
During ACN communication stop, mirror heater does not operate (operates during electric power control ECU communication stop) | None |
| Foot area illumination |
|
|
|
During IDT communication stop: If malfunction occurs when person sensor is operating, after foot area illumination control's timer illumination time elapses, foot area illumination turns OFF | None |
| Driver seat memory | Front Power Seat ECU and Switch LH |
|
Front Power Seat ECU and Switch LH | Driver side seat memory operation stops, or does not operate | None |
| Passenger seat full front return | Front Power Seat ECU and Switch RH |
|
Front Power Seat ECU and Switch RH |
|
RCN: Warning buzzer sounds during rear seat slide, reclining and manual operation |
| Passenger side rear ottoman seat | Rear Power Seat Module Switch |
|
Front Power Seat ECU and Switch RH |
|
RCN: Warning buzzer sounds during rear seat slide, reclining and manual operation |
| Rear seat memory | Rear Power Seat Module Switch |
|
- | Rear seat memory operation stops, or does not operate | None |
| Seat return for rear seat (when rear seat doors are opened) | Rear Power Seat Module Switch |
|
- | Rear seat return does not operate | None |
| Seat return for rear seat (via switch) | Rear Power Seat Module Switch |
|
- | Rear seat return does not operate | None |
| Rear seat heater (ventilation) | Rear Power Seat Module Switch |
|
- | Rear seat heater does not operate | None |
| Belt anchor call control (driver seat and passenger seat) | Rear Junction Block ECU |
|
Rear Junction Block ECU |
|
None |
| Wiper control | Front Controller |
|
Front Controller |
|
None |
| Washer motor control | Front Controller |
|
Front Controller |
|
None |
| Vehicle speed display | No. 1 Meter ECU (V bus) | Skid Control ECU (V bus) | - | Vehicle speed display not possible | While vehicle is driven, vehicle speed display is 0 km/h (mph) |
| Tachometer display | No. 1 Meter ECU (V bus) | ECM (V bus) | - | Tachometer display not possible | While vehicle is driven, tachometer display is 0 rpm |
| Water temperature display | No. 1 Meter ECU (V bus) | ECM (V bus) | - | Water temperature display not possible | Water temperature needle points to less than C |
| Fuel gauge | No. 1 Meter ECU (V bus) |
|
- | Fuel display not possible | Fuel needle points to less than E |
| Odometer/Trip meter | No. 1 Meter ECU (V bus) | Skid Control ECU (V bus) | - | Quantity survey not possible | None |
| A/T shift indicator | No. 1 Meter ECU (V bus) | ECM (V bus) | - | Shift display turns OFF | None |
| Rheostat control | Main Body ECU (MS bus) | Main Body ECU (MS bus) | No. 1 Meter ECU (MS bus) | Rheostat control impossible | None |
| Buzzer |
|
|
No. 1 Meter ECU (MS bus) | Buzzer stops | None |
| Parking Assist ECU | Skid Control ECU | Skid Control ECU | IPA operation stops | None | |
| Combination meter diagnosis (telltale) |
|
|
No. 1 Meter ECU (V bus) | Indicator illuminates | Active operation indicator illuminates |
| Potential cruising distance | No. 1 Meter ECU (V bus) |
|
No. 1 Meter ECU (V bus) | Value display is not possible | None |
| Average overall mileage | No. 1 Meter ECU (V bus) |
|
No. 1 Meter ECU (V bus) | Value display is not possible | None |
| Current mileage | No. 1 Meter ECU (V bus) |
|
No. 1 Meter ECU (V bus) | Value display is not possible | None |
| Average mileage after lubrication | No. 1 Meter ECU (V bus) |
|
No. 1 Meter ECU (V bus) | Value display is not possible | None |
| Traveling distance after lubrication | No. 1 Meter ECU (V bus) | Skid Control ECU (V bus) | No. 1 Meter ECU (V bus) | Value display is not possible | None |
| Average overall speed | No. 1 Meter ECU (V bus) | Skid Control ECU (V bus) | No. 1 Meter ECU (V bus) | Value display is not possible | None |
| Charge control | Electric Power Control ECU |
|
- | No vehicle symptoms | None |
| Load control | Electric Power Control ECU |
|
- | No vehicle symptoms | None |
| Control while parked | Electric Power Control ECU | Main Body ECU (V bus) | - | No vehicle symptoms | None |
| Power system malfunction detection | Electric Power Control ECU |
|
- | No vehicle symptoms | None |
| Air conditioning | Air Conditioning Amplifier |
|
Air Conditioning Amplifier | Compressor OFF Set temperature: Fahrenheit default operates (if communication stop occurs, previous operation is maintained) | Outside temperature "E" is displayed |
| Air conditioning related switch operation information (EMVN) | Air Conditioning Amplifier | Display and Navigation (Multi-display) | Air Conditioning Amplifier | No vehicle symptoms | When A/C warning on screen display instruction signal is received: Navigation screen displays "Check the condition to the air conditioner" |
| Rear air conditioning | Rear Power Seat Module Switch |
|
Rear Power Seat Module Switch | Rear air conditioning stops | None |
| Rear A/C magnet valve | Air Conditioning Amplifier |
|
Rear Junction Block ECU | Rear air conditioning magnet valve output OFF | None |
| Rear defogger | Air Conditioning Amplifier |
|
Front Controller | ACN: operation not possible | None |
| Wiper deicer | Air Conditioning Amplifier |
|
Front Controller | ACN: operation not possible | None |
| RFC fan control | ECM (V bus) | ECM (V bus) | Front Controller | Operates at 100% output | None |
| Headlight swivel/ leveling control | AFS ECU |
|
- | Swivel control stops Leveling control continues | Navigation screen displays "Check AFS", and master caution is illuminated AFS indicator blinks |
| Tilt and telescopic control | Multiplex tilt and Telescopic ECU |
|
Multiplex tilt and Telescopic ECU |
|
None |
| Near-infrared floodlight HI beam illumination control (Used for pedestrian detection) | Driving Support ECU (MS bus) | Driving Support ECU (MS bus) | Front Controller | HI beam turns OFF | None |
| Horn control | Main Body ECU (MS bus) |
|
Front Controller | Horn does not operate | None |
| Fuel lid opener | Main Body ECU (MS bus) | Main Body ECU (MS bus) | Rear Junction Block ECU | Open and close is not possible | None |
| Rear door sunshade |
|
|
|
Rear sunshade stops (if operating, continues operating) | None |
| Rear sunshade | Main Body ECU (MS bus) |
|
Rear Junction Block ECU |
|
None |
| Event recorder | Center Airbag Sensor | ECM (V bus) | - | Event recorder stops | None |
| NAVI-AI-SHIFT control | ECM (V bus) |
|
ECM (V bus) | Control does not start (on navigation screen, "NAVI-AI-SHIFT" is selected) | None |
| Control for changing air conditioning from FRESH to RECIRC when entering tunnel | Air Conditioning Amplifier |
|
Air Conditioning Amplifier | Control does not start (FRESH/RECIRC change switch's "AUTO" is selected) | None |
| Tunnel prediction AFS control | AFS ECU |
|
AFS ECU | Control does not start (Light switch "AUTO" and AFS "ON" are selected) | None |
| Navigation system cooperation AVS control | Suspension Control ECU (Steering bus) |
|
Suspension Control ECU (Steering bus) | Control does not start | None |
| Rear view monitor control (for depicting guide/course line) | Display and Navigation (Multi-display) |
|
- | Display's expected course lines are erased | Navigation screen displays "Guidance unavailable" |
| ACC control |
|
|
- | When vehicle is stopped: ACC control is canceled and oil pressure is slowly decreased; then control is prohibited When vehicle is driven or control is operating: ACC control is canceled |
|
| PCS control |
|
|
- | No vehicle symptoms |
|
| Damping force control function |
|
|
|
No vehicle symptoms | None |
| Vehicle height adjustment function |
|
|
- | No vehicle symptoms | None |
| APGS control | Parking Assist ECU |
|
- | When vehicle is stopped: APGS control start is not possible When vehicle is driven or control is operating: APGS control start is stopped | During ENG, Electronically controlled brake, Electric parking brake, VGR, EPS, STR and AFS communication stop: Navigation screen: "Check APGS system" Audio: "The Guidance has been canceled" During YGS communication stop: No display and no B buzzer operation (IPA control start and idle speed control not possible |
| Column guide transition | Parking Assist ECU | Skid Control ECU (Steering bus) | - | When vehicle is stopped: During column guide display: Because column guide is displayed based on yaw rate information, user cannot detect communication malfunction Information setting screen: When vehicle speed is increasing, vehicle speed is confirmed because switch is not displayed. When vehicle is driven or control is operating: After vehicle speed has increased, switch changes from not displayed to displayed When vehicle is driven or control is operating: Information setting screen: When vehicle speed is increasing, vehicle speed is confirmed because switch is not displayed. When vehicle is driven or control is operating: After vehicle speed has increased, switch changes from not displayed to displayed | None |
| Clearance sonar function |
|
|
- | When there is vehicle speed signal stop or shift signal stop: Obstacle detection stops When other signals stop: Vehicle condition before signal stop is maintained | None |
| VDIM control |
|
|
- | When vehicle is stopped: No vehicle behavior When vehicle is driven or control is operating: After backup control (vehicle behavior stable) is complete, changes to normal brake operation and then control is prohibited |
|
| Brake hold control | Skid Control ECU (Braking and Driving bus) |
|
- | When vehicle is stopped: When brakes or accelerator pedal is depressed, oil pressure is released and control is prohibited When vehicle is driven or control is operating: No recognizable vehicle behavior |
|
| Emergency stop light activation (during radar cruising) | Skid Control ECU (V bus) |
|
Rear Junction Block ECU | Emergency stop light does not operate | None |
| Millimeter wave linked pre-collision system | Seat Belt Control ECU |
|
- | No vehicle symptoms | When PCS is malfunctioning:
When millimeter wave radar is malfunctioning:
|
| Pre-collision emergency braking | Seat Belt Control ECU |
|
- | No vehicle symptoms | When PCS is malfunctioning:
When millimeter wave radar is malfunctioning:
|
| EPS assist control |
|
|
|
Only during vehicle speed (Electronically controlled brake) communication stop, assist control when vehicle speed is 100 km/h (160mph)is provided (for other situations, no vehicle behavior) | During communication stop of vehicle speed (Electronically controlled brake) or steering angle information (VGR):
|
| VGRS control |
|
|
- | VGRS control is prohibited | Multi-information display: "Check VGRS" is displayed and master caution is illuminated |
| VDM-J3 control | Steering Control ECU (Steering bus) |
|
- | VDM-p control is prohibited | Multi-information display: "Check VSC system" is displayed and master caution is illuminated |
| Dynamic parking brake (during manual lock release operation) | Electric Parking Brake ECU | Skid Control ECU (Braking and Driving bus) | Electric Parking Brake ECU | When vehicle is driven or control is operating: Automatic release is not operated, and tires lock |
|
| Shift-linked parking brake (when select switch is AUTO) | Electric Parking Brake ECU |
|
Electric Parking Brake ECU | When vehicle is stopped: Linked operation with shift lever is not possible When vehicle is driven or control is operating: Shift-linked select switch light turns OFF, and shift-linked operation does not occur |
|
| Tension adjustment | Electric Parking Brake ECU | Yaw Rate Sensor | - | When vehicle is stopped:
|
|
| Backup oil pressure maintenance for when vehicle is stopped (brake hold) | Electric Parking Brake ECU |
|
- | When vehicle is stopped:
|
|
| MS bus monitoring function | Main Body ECU (MS bus) |
|
- | Communication malfunction is detected | None |
| Steering bus monitoring function | Skid Control ECU (Steering bus) |
|
- | Communication malfunction is detected | None |
| Braking/Driving system bus monitoring function | ECM (Braking and Driving bus) |
|
- | Communication malfunction is detected | None |