LIGHTING SYSTEM > FAIL-SAFE CHART

for Preparation Click here

FAIL-SAFE

Headlight beam level control ECU
The headlight beam level control ECU executes the fail-safe actions listed below in accordance with the item that has been detected.

Item
Outline
Detection of Abnormal Input Voltage
If voltage that is input to headlight beam level control ECU deviates from operating voltage (9 to 16 V), ECU stops illuminating the headlights, and resumes illuminating headlight once the voltage reverts to the operating voltage range
However, if input voltage decreases after headlights have illuminated, headlight will remain illuminated until bulbs are extinguished
Detection of Abnormal Output (open or short circuit) or Flashing Bulb
If abnormal condition (open or short circuit) occurs in voltage that is output by headlight beam level control ECU, or if bulb flashes, ECU stops illuminating headlights and will maintain this state until power is reinstated (by turning headlight control switch from ON or OFF)
Detection of Bulb Open
If bulb is not inserted in its socket, ECU stops generating high voltage until bulb is inserted correctly and power is reinstated (by turning headlight control switch from OFF to ON or turning engine switch from off to on (IG))

Headlight beam level control system
The headlight beam level control ECU operates in the fail-safe mode if an abnormal condition such as those listed below has been detected, and illuminates the automatic headlight leveling system warning light in the combination meter.

Item
Abnormality Detection Condition
Description of Control
Actuator
Open or Short
Holds beam at position of actuator when abnormality has been detected
Height Control Sensor
Signal Level Abnormality
Returns beam to actuator's initial set position if abnormality has been detected higher than initial set position
Holds beam at position of actuator when abnormality has been detected, if abnormality has been detected lower than initial set position
Headlight Beam Level Control ECU
When an abnormal processing of the CPU has been detected
Holds beam at position of actuator when abnormality has been detected
Generator Signal
When CHG- is low and vehicle speed is 0 km/h (0 mph) or more for 10 seconds
Continue light control
Vehicle Speed Signal
When one side is 0 km/h (0 mph) and other side is more than 0 km/h (mph)
Continue light control using normal vehicle speed signal

Item	Outline
Detection of Abnormal Input Voltage	If voltage that is input to headlight beam level control ECU deviates from operating voltage (9 to 16 V), ECU stops illuminating the headlights, and resumes illuminating headlight once the voltage reverts to the operating voltage range However, if input voltage decreases after headlights have illuminated, headlight will remain illuminated until bulbs are extinguished
Detection of Abnormal Output (open or short circuit) or Flashing Bulb	If abnormal condition (open or short circuit) occurs in voltage that is output by headlight beam level control ECU, or if bulb flashes, ECU stops illuminating headlights and will maintain this state until power is reinstated (by turning headlight control switch from ON or OFF)
Detection of Bulb Open	If bulb is not inserted in its socket, ECU stops generating high voltage until bulb is inserted correctly and power is reinstated (by turning headlight control switch from OFF to ON or turning engine switch from off to on (IG))

Item	Abnormality Detection Condition	Description of Control
Actuator	Open or Short	Holds beam at position of actuator when abnormality has been detected
Height Control Sensor	Signal Level Abnormality	Returns beam to actuator's initial set position if abnormality has been detected higher than initial set position Holds beam at position of actuator when abnormality has been detected, if abnormality has been detected lower than initial set position
Headlight Beam Level Control ECU	When an abnormal processing of the CPU has been detected	Holds beam at position of actuator when abnormality has been detected
Generator Signal	When CHG- is low and vehicle speed is 0 km/h (0 mph) or more for 10 seconds	Continue light control
Vehicle Speed Signal	When one side is 0 km/h (0 mph) and other side is more than 0 km/h (mph)	Continue light control using normal vehicle speed signal