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Fail-Safe Chart

FAIL-SAFE FUNCTION

When communication fails in any of the CAN bus wires (communication wires) 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 following chart shows the relationships between components, system functions, and effects of communication failure on these functions. (For further details, see the pages for each system.)

FAIL-SAFE CHART

Function (Function Description)	Control Master	System Related	Fail-safe Operation	DTC (Driver Detectable)
VSC control*1 (Controls driving force while VSC in operation)	Skid Control ECU	ECM Steering Angle Sensor Yaw Rate Sensor	VSC control is inoperative (VSC control gradually stops)	U0073, U0100, U0123, U0124, U0126 (Warning light comes on)
VSC control*1 (Engine power control by VSC/TRC)	Skid Control ECU	ECM Steering Angle Sensor Yaw Rate Sensor	VSC control is inoperative (VSC control gradually stops)	U0073, U0100, U0123, U0124, U0126 (Warning light comes on)
ABS control (Controls driving force while ABS in operation)	Skid Control ECU	Yaw Rate Sensor*1	Control inoperative (gradually stops controlling during ABS control)	U0073, U0123, U0124*1 (Warning light comes on)
Electric power steering (Speed of vehicle induction type torque control)	Power Steering ECU	ECM Skid Control ECU Steering Angle Sensor Combination Meter	Depression of EPS assist (Deterioration of steering)	U0100, U0129 (VSC failure: warning light comes on, and decrease of assistance power at vehicle speed 70 km/h) (ECM failure: Warning light comes on [only before assist beginning])
Meter display (Displays operation condition and DTCs)	Combination Meter	ECM Skid Control ECU Center Airbag Sensor Assembly Main Body ECU Air Conditioning amplifier 4WD Control ECU Power Steering ECU	Light does not come on, illuminates abnormally, or blinks abnormally	Abnormal light illumination
Air conditioning control	Air Conditioning Amplifier	ECM Combination Meter Main Body ECU	Air conditioning function and PTC heater function stop	B1499 (Air Conditioning inoperative)
CAN No. 2 bus monitoring function	Network Gateway ECU	4WD Control ECU	Communication error is detected	U0114, U1002 (Not detectable)
4WD control*2 (Distribution of the driving force in the rear and front wheel is controlled by running state of the vehicle)	4WD Control ECU	ECM Skid Control ECU Steering Angle Sensor	4WD function stops (the same as 2WD)	U0073, U0100, U0126, U0129 (Warning light comes on)
HINT: 1: w/VSC 2: for 4WD