FAIL-SAFE FUNCTION
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.
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
|
Air conditioning amplifier assembly | ECM | Control is performed based on default coolant temperature of 80°C (176°F). | - | U0100 (Air conditioning amplifier assembly) |
| Compressor Control
|
Air conditioning amplifier assembly | ECM | Control is performed based on default engine speed of 0 rpm. | - | U0100 (Air conditioning amplifier assembly) |
| Simple Load Control
|
Air conditioning amplifier assembly | Power steering ECU with motor assembly | Load control is not performed. | - | U0131 (Air conditioning amplifier assembly) |
| Panel Control
|
Air conditioning amplifier assembly | Multi-media module receiver assembly | Air inlet mode does not change. | - | U0163 (Air conditioning amplifier assembly) |
| Panel Dimming Control
|
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
|
Air conditioning amplifier assembly | Main body ECU (Multiplex network body ECU) | Maintains the latest state. | - | U0142 (Air conditioning amplifier assembly) |
| Ambient Temperature Correction Control
|
Air conditioning amplifier assembly | Combination meter assembly | Control is performed based on default vehicle speed of 0 km/h (0 mph). |
|
U0155 (Air conditioning amplifier assembly) |
| Air Conditioning Eco Mode Control
|
Air conditioning amplifier assembly | ECM | Maintains the latest state (Maintained in normal condition after reset). | - | U0100 (Air conditioning amplifier assembly) |
| Electric Load Control
|
ECM |
|
Idle up according to electric load is not performed. | Not possible. (Idle speed changes) | - |
| Air Conditioning Cooperative Operation
|
ECM | Air conditioning amplifier assembly | Air conditioning system does not use cooperative controls. (Idle up is not performed.) | Air conditioning system does not operate. | - |
| PTC Heater
|
ECM | Air conditioning amplifier assembly | Engine idle speed changes. | Heating performance deteriorates. PTC heater does not operate. |
- |
| Charge Control
|
ECM |
|
Idle up according to charging request is not performed. | Taillights flicker and blower airflow changes. | - |
| Eco Control
|
ECM |
|
Eco mode does not operate. | - | - |
| Cruise Control
|
ECM |
|
Cruise control does not operate. |
|
- |
| Power Steering Control
|
Power steering ECU with motor assembly |
|
When communication with ECM is interrupted:
When communication with skid control ECU is interrupted:
|
EPS warning light illuminates. | U0100 U0129 (Power steering ECU with motor assembly) |
| Steering Assist Calculation
|
Power steering ECU with motor assembly |
|
Control continues based on a default speed of 100 km/h (62 mph) because vehicle speed is unrecognizable. (Steering wheel feels heavy when the vehicle speed is below 100 km/h (62 mph) and feels light at speeds above 100 km/h (62 mph).) | EPS warning light illuminates. | U0129 (Power steering ECU with motor assembly) |
| Assist Map Selection
|
Power steering ECU with motor assembly | ECM | Default map is used to assist because proper assist map cannot be selected. (Steering feel may be different.) | EPS warning light illuminates. | C1582 (Power steering ECU with motor assembly) |
| Steering/Steering angle sensor initialization and zero point learning. | Power steering ECU with motor assembly |
|
Steering initialization and zero point learning are not performed. | EPS warning light illuminates. | U0129 (Power steering ECU with motor assembly) |
| Lane Departure Alert System
|
Lane departure warning camera |
|
Lane recognition and buzzer warning are canceled. |
|
U0101 U0104 U0123 U0129 U0142 U0155 (Lane departure warning camera) |
| Automatic High Beam System
|
Lane departure warning camera |
|
Maintains the same condition. | Displays messages on the multi-information display. | U0101 U0123 U0129 U0142 (Lane departure warning camera) |
| Vehicle Speed Display | Combination meter assembly | Brake actuator assembly (Skid control ECU) | None |
|
U0129 (Combination meter assembly) |
| Tachometer Display | Combination meter assembly | ECM | None |
|
U0100 (Combination meter assembly) |
| Airbag Warning
|
Combination meter assembly | Airbag sensor assembly | None | Airbag warning light illuminates. | U0151 (Combination meter assembly) |
| EPS Warning
|
Combination meter assembly | Power steering ECU with motor assembly | None | EPS warning light illuminates. | U0131 (Combination meter assembly) |
| Vehicle Customization
|
Combination meter assembly | Main body ECU (Multiplex network body ECU) | None | Multi-information display does not display vehicle customization items. | U0142 (Combination meter assembly) |
| SLIP Warning
|
Combination meter assembly | Brake actuator assembly (Skid control ECU) | None | SLIP indicator illuminates. | - |
| Engine Coolant Temperature Receiver Gauge Control | Combination meter assembly | ECM | None | Needle of engine coolant temperature receiver gauge is at the middle or below. | - |
| Tire Pressure Monitor System
|
Combination meter assembly | Main body ECU (Multiplex network body ECU) | None | Tire pressure warning light illuminates. | - |
| Tire Pressure Monitor System
|
Combination meter assembly | Main body ECU (Multiplex network body ECU) | None | Tire pressure is not displayed. | - |
| ABS Control | Brake actuator assembly (Skid control ECU) | Airbag sensor assembly |
When back-up control (vehicle behavior stabilization) is complete, braking returns to normal operation and further control is prohibited.
Control will not be started. |
|
U0073 U0124 (Brake actuator assembly (Skid control ECU)) |
| TRC/VSC Control | Brake actuator assembly (Skid control ECU) |
|
When back-up control (vehicle behavior stabilization) is complete, braking returns to normal operation and further control is prohibited.
Control will not be started. |
|
U0073 U0100 U0124 U0126 (Brake actuator assembly (Skid control ECU)) |
| Air Conditioning Control
|
Multi-media module receiver assembly | Air conditioning amplifier assembly |
|
A message indicating to check air conditioning amplifier connection appears on multi-display. | U0073 (Multi-media module receiver assembly) |
| Fuel Consumption Display
|
Multi-media module receiver assembly |
|
When communication with ECM or skid control ECU is interrupted:
When communication with combination meter is interrupted:
|
- | U0100 U0129 U0155 (Multi-media module receiver assembly) |
| Destination Identification
|
Multi-media module receiver assembly | Main body ECU (Multiplex network body ECU) | Destination is identified based on information received before communication is interrupted. | Time zone and language selection screen are different from actual destination. | U0140 (Multi-media module receiver assembly) |
| Vehicle Customization Function
|
Multi-media module receiver assembly |
|
When an application that uses phase 4 remote communication is activated (customization/remote diagnosis), the process will be performed regardless of main body ECU (multiplex network body ECU) remote communication permit/ prohibit state. | Related customization items are not displayed or do not change to set values. | U0073 (Multi-media module receiver assembly) |
| Rear View Monitor System
|
Multi-media module receiver assembly |
|
None | Screen does not change to the camera screen. | U0100 (Multi-media module receiver assembly) |
| Rear View Monitor Control
|
Multi-media module receiver assembly |
|
|
- | U0100 U0126 U0129 U0140 (Multi-media module receiver assembly) |
| Entry Function
|
|
|
Entry unlock is performed again. |
|
U0100 U0155 U0327 (Main body ECU (Multiplex network body ECU)) |
| U0100 U0142 U0155 (Certification ECU (Smart key ECU assembly)) |
|||||
| Engine Switch Backlighting Control
|
Certification ECU (Smart key ECU assembly) | Main body ECU (Multiplex network body ECU) | Engine switch backlighting does not illuminate according to interior lights operation. | - | U0142 Certification ECU (Smart key ECU assembly) |
| Door Lock
|
Main body ECU (Multiplex network body ECU) |
|
|
- | U0100 U0101 U0151 U0155 (Main body ECU (Multiplex network body ECU)) |
| Display Automatic Dimming
|
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
|
Main body ECU (Multiplex network body ECU) |
|
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) |
|
Interior lights turn off. | When communication with certification ECU (smart key ECU assembly) is interrupted:
|
U0101 U0327 (Main body ECU (Multiplex network body ECU)) |
| Seat and Mirror Control | Main body ECU (Multiplex network body ECU) |
|
|
- | U0120 U0199 U0200 U0208 U0155 U0327 U1115 (Main body ECU (Multiplex network body ECU)) |
| Entry Function/Wireless Control | Certification ECU (Smart key ECU assembly) | Main body ECU (Multiplex network body ECU) | Entry lock/unlock control is not possible. | - | U0327 (Main body ECU (Multiplex network body ECU)) |
| Daytime Running Light Control | Main body ECU (Multiplex network body ECU) | ECM | Daytime running light control does not operate. | - | U0100 (Main body ECU (Multiplex network body ECU)) |
| Vehicle Customization | Main body ECU (Multiplex network body ECU) |
|
Vehicle customization functions do not operate. | - | U0155 U0163 U0327 (Main body ECU (Multiplex network body ECU)) |
| Tire Pressure Monitor System
|
Main body ECU (Multiplex network body ECU) | Combination meter assembly | - | TPMS indicator light blinks and then illuminates. | U0155 (Main body ECU (Multiplex network body ECU)) |
| Automatic High Beam System
|
Main body ECU (Multiplex network body ECU) | Lane departure warning camera | Maintains the same condition. | Displays messages on the multi-information display. | U0182 (Main body ECU (Multiplex network body ECU)) |
| Engine Start/Stop Switch (Power Source Mode Change)
|
Main body ECU (Multiplex network body ECU) |
|
- | Engine start assist messages are not displayed on the multi-display. | U0100 Certification ECU (Smart key ECU assembly) |
| Power Tilt and Power Telescopic Steering Column Control | Multiplex tilt and telescopic ECU |
|
- |
|
U0142 U0208 (Multiplex tilt and telescopic ECU) |
| Seat Position Memory System
|
Front power seat switch LH |
|
Controls the seat position based on operation conditions. | - | - |
| Mirror Surface Adjustment |
|
Main body ECU (Multiplex network body ECU) | Mirror surface position cannot be memorized or recalled. | - | U0142 (Outer mirror control ECU assembly) |
| Mirror Heaters |
|
|
Mirror heaters do not operate. | - | - |
| Mirror Retract/Return Operation |
|
Main body ECU (Multiplex network body ECU) | Mirrors cannot be retracted or returned. | - | - |
| Reverse-shift Linked Door Mirror Operation |
|
Main body ECU (Multiplex network body ECU) | Reverse-shift linked door mirror operation. | - | - |
| Mirror Surface Position Memory and Recall |
|
Main body ECU (Multiplex network body ECU) | Mirror surface position cannot be memorized or recalled. | - | - |
| Seat Memory Switch Signal Forwarding
|
Main body ECU (Multiplex network body ECU) |
|
Seat position memory settings cannot be memorized or recalled. | - | - |
| Power Trunk Lid System
|
Luggage closer motor assembly |
|
|
- | - |
| Luggage Compartment Door Closer System
|
Luggage closer motor assembly |
|
Automatic close function cannot reverse operation while operating. | - | - |
| Courtesy Switch Signal Forwarding
|
Luggage closer motor assembly | Main body ECU (Multiplex network body ECU) | - | Door ajar warning light does not illuminate even though the luggage compartment door is open. | - |
| Dynamic Radar Cruise Control System
|
ECM |
|
Control stops |
|
U0125 U0126 U0129 (ECM) |
| Pre-crash Safety System
|
Driving support ECU assembly |
|
Control stops. |
|
U0125 U0126 U0129 U0142 U1100 (Driving support ECU assembly) |
| Lexus Parking Assist-sensor System Control
|
Clearance warning ECU assembly | ECM | Obstacle detection is stopped. | - | U0101 (Clearance warning ECU assembly) |
| Lexus Parking Assist-sensor System Control
|
Clearance warning ECU assembly | Combination meter assembly | Obstacle detection is stopped. | - | U0155 (Clearance warning ECU assembly) |
| Pre-crash Safety System (Operation Condition 1)
|
Seat belt control ECU |
|
Control stops | PCS indicator light flashes. | U0129 U0140 U0151 (Seat belt control ECU) |
| Pre-crash Safety System (Operation Condition 2)
|
Seat belt control ECU |
|
Control stops | PCS indicator light flashes. | U0129 U0140 U0151 U1104 (Seat belt control ECU) |
| Blind Spot Monitor Control
|
Blind spot monitor sensor LH |
|
Blind spot monitor control is prohibited. | Blind spot monitor system warning light on the combination meter turns on. | U0100 U0126 U0129 U0142 U0232 (Blind spot monitor sensor LH) |
| Gateway System (Between V bus and sub bus 2)
|
Network gateway ECU | w/ Pre-crash safety system:
|
- | - | U0104 U0233 U1002 U1100 (Network gateway ECU) |
| w/o Pre-crash safety system:
|
- | - | U0233 U023A U1002 (Network gateway ECU) |