Fail-Safe Chart

WARNING: This page is about a different car, the 2006 Lexus RX 400h. However, it is still accessible from the selected car via links, so may be relevant.

FAIL-SAFE FUNCTION

When communication fails in any of the CAN bus lines (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.

FAIL-SAFE CHART

Function	HV Control ECU (HV)	HV Control ECU (ENGINE)	Skid Control ECU	Steering Control ECU	Yaw Rate Sensor	Action when communication is disabled	DTC detection (if the driver can recognize a malfunction)
Toyota Hybrid System-II (THS-II) Control (to optimize the combination between the engine and motor drive power for driving	X	x	-	-	-	Safe running	Recognizable (HV caution light and MIL come on)
Regenerative Braking (the motor acts as a generator that depends on wheel rotation and generates electricity to be stored in the HV battery)	x	-	X	-	-	Regenerative braking will stop.	Recognizable. (VSC, ABS, ECB, and 4WD warning lights come on)
VSC Control (to control the braking force when the VSC is activated)	x	-	X	x	x	VSC function will stop.	Recognizable. (VSC, ABS, ECB, and 4WD warning lights come on)
Laser Cruise (to maintain a safe distance from other vehicles)	X	-	x	x	x	Laser cruise will be inoperative.	Recognizable. (Cruise warning light blinks)
Electric Power Steering (to calculate the assist current from the torque sensor value and vehicle speed, and outputs the current to the motor)	x	-	x	x	-	When communication with the THS-II is disabled: Assist will stop. When communication with the ECB is disabled: Control will continue using assist force that is equivalent to the vehicle speed of 100 km/h (62.14 mile/h)	Recognizable. (EPS warning light blinks)
Rear View Monitor (to display the direction of movement when reversing)	x	-	-	-	-	Rear View monitor will be inoperative.	Recognizable with the screen not displaying the rear view monitor.
Multi-Information Display (to display operating condition, shift position, and DTC)	x	x	x	-	-	Light does not come on, or remains on	(Recognizable tire air pressure, BRAKE, ABS, P/S lights come on.Shift position light goes off)

HINT:

X: Control master
x: System related

FAIL-SAFE CHART

Function	Power steering ECU	Distance Control ECU	Television Camera ECU	Network gateway ECU	Action when communication is disabled	DTC detection (if the driver can recognize a malfunction)
Toyota Hybrid System-II (THS-II) Control (to optimize the combination between the engine and motor drive power for driving	-	-	-	-	Safe running	Recognizable (HV caution light and MIL come on)
Regenerative Braking (the motor acts as a generator that depends on wheel rotation and generates electricity to be stored in the HV battery)	-	-	-	-	Regenerative braking will stop.	Recognizable. (VSC, ABS, ECB, and 4WD warning lights come on)
VSC Control (to control the braking force when the VSC is activated)	-	-	-	-	VSC function will stop.	Recognizable. (VSC, ABS, ECB, and 4WD warning lights come on)
Laser Cruise (to maintain a safe distance from other vehicles)	-	x	-	-	Laser cruise will be inoperative.	Recognizable. (Cruise warning light blinks)
Electric Power Steering (to calculate the assist current from the torque sensor value and vehicle speed, and outputs the current to the motor)	X	-	-	-	When communication with the THS-II is disabled: Assist will stop. When communication with the ECB is disabled: Control will continue using assist force that is equivalent to the vehicle speed of 100 km/h ( mile/h)	Recognizable. (EPS warning light blinks)
Rear View Monitor (to display the direction of movement when reversing)	-	-	X	-	Rear View monitor will be inoperative.	Recognizable with the rear view monitor.
Multi-Information Display (to display operating condition, shift position, and DTC)	x	-	-	X Meter	Light does not come on, or remains on	(Recognizable tire air pressure, BRAKE, ABS, P/S lights come on.Shift position light goes off)

HINT:

X: Control master
x: System related