Lexus IS250 · Service Manual COMMUNICATION SYSTEM

FAIL-SAFE CHART

System information

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.

Effects on each system when communication is impossible. (For further details, see the pages for each system.)

Function	ECM	Skid Control ECU	Steering Angle Sensor	Yaw Rate Sensor	Distance Control ECU	Condition when communication is impossible	DTC detection (Driver detectable)
VSC Control (Controls driving force while VSC is in operation)	○	●	○	○	-	VSC function stops	Detectable (Light comes on)
Dynamic Radar Cruise (Maintains vehicle-to- vehicle distance)	○	○	-	-	●	Vehicle-to-Vehicle distance control does not operate	Detectable (Light comes on)
Pre-crash Control (Requests braking and seat belt tightening when an unavoidable collision possibility is detected)	-	○	-	-	○	Pre-crash is inoperative	Detectable (Light comes on)
Electric power steering (Outputs the assist current)	○	○	○	-	-	Control continues with steering assist force based on a vehicle speed of 100 km/h (62.2 mile/h) or equivalent	Detectable (Light comes on)
Parking assist monitor system (exterior view from rear of vehicle while reversing)	○	-	○	-	-	Parking assist monitor system function stops	Detectable (recognized when vehicle direction is not displayed)
Meter Display (Displays operation condition and DTCs)	○	○	-	-	-	Light does not come on or remains on	Can be recognized due to abnormal operation of the light

Function	Seat belt control ECU	Gateway ECU	Power steering ECU	Television Camera ECU	Condition when communication is impossible	DTC detection (Driver detectable)
VSC Control (Controls driving force while VSC is in operation)	-	-	-	-	VSC function stops	Detectable (Light comes on)
Dynamic Radar Cruise (Maintains vehicle-to- vehicle distance)	○	-	-	-	Vehicle-to- Vehicle distance control does not operate	Detectable (Light comes on)
Pre-crash Control (Requests braking and seat belt tightening when an unavoidable collision possibility is detected)	●	-	-	-	Pre-crash is inoperative	Detectable (Light comes on)
Electric power steering (Outputs the assist current)	-	-	●	-	Control continues with steering assist force based on a vehicle speed of 100 km/h (62.2 mile/h) or equivalent	Detectable (Light comes on)
Parking assist monitor system (exterior view from rear of vehicle while reversing)	-	-	-	●	Parking assist monitor system function stops	Detectable (recognized when vehicle direction is not displayed)
Meter Display (Displays operation condition and DTCs)	-	● (Meter)	-	○	Light does not come on or remains on	Can be recognized due to abnormal operation of the light

HINT:

●: Control master

○: System related