Fail-Safe Chart

WARNING: This page is about a different car, the 2008 Lexus LS 600hL. However, it is still accessible from the selected car via links, so may be relevant.

Headlight control ECU

The headlight control ECU operates in the fail-safe mode if an abnormal condition such as those listed below has been detected.

for HID Headlight

HID HEADLIGHT ITEM CHART

Item	Outline
Detection of abnormal input voltage (High input voltage)	If voltage that is input to the headlight control ECU is approximately 20 V or more, the ECU stops illuminating the headlights, and resumes when the voltage drops to 16 V or less
Detection of abnormal input voltage (Low input voltage)	If voltage that is input to the headlight control ECU is 6 V or less, the ECU stops illuminating the low beam headlights, and resumes when the voltage is 10 V or more
Detection of abnormal output Open in output side circuit Short between output terminals Short between output terminal and body ground	If an abnormal condition occurs in the voltage that is output by the headlight control ECU, the ECU stops illuminating the low beam headlights and will maintain this state until the power is reinstated (by turning the light control switch from OFF to HEAD)
Detection of bulb flashing	If the bulb flashing repeats within approximately 5 seconds and continues for approximately 60 seconds, the headlight control ECU stops illuminating low beam headlights and will maintain this state until the power is reinstated (by turning the light control switch from OFF to HEAD)
Detection of abnormal light voltage (Low light voltage)	After approximately 80 seconds since input voltage is supplied, if the light voltage is below approximately 31 V for approximately 0 5 seconds, the headlight control ECU stops illuminating the low beam headlights and will maintain this state until the power is reinstated (by turning the light control switch from OFF to HEAD)
Detection of abnormal light voltage (High light voltage)	If the light voltage is above approximately 69 V for approximately 0 5 seconds, the headlight control ECU stops illuminating the low beam headlights and will maintain this state until the power is reinstated (by turning the light control switch from OFF to HEAD)

for LED Headlight

HID HEADLIGHT ITEM CHART

Item	Outline
Detection of abnormal input voltage (High input voltage)	If voltage that is input to the headlight control ECU is approximately 20 V or more, the ECU stops illuminating the headlights, and resumes when the voltage drops to 16 V or less
Detection of abnormal input voltage (Low input voltage)	If voltage that is input to the headlight control ECU is 7 V or less, the ECU stops illuminating the low beam headlights, and resumes when the voltage is 10 V or more
Detection of abnormal output Open in output side circuit Short between output terminal and body ground	If an abnormal condition occurs in the voltage that is output by the headlight control ECU, the ECU stops illuminating the low beam headlights and will maintain this state until the power is reinstated (by turning the light control switch from OFF to HEAD)

AFS ECU

If the AFS ECU detects a malfunction in the automatic headlight beam level control system or intelligent AFS, it will take the actions indicated in the table below.

AFS ECU REFERENCE CHART

Trouble Area	Leveling Fail-safe Control	Swivel Fail-safe Control	AFS OFF Indicator Light
Headlight Swivel Motor Malfunction	Continues to control with both headlight leveling motors lower than current position by 0 65°	Stops malfunctioning swivel motor at current position	Flash
Steering Angle Sensor Signal Malfunction	Continues to control	Returns both headlight swivel motors back to front
Speed Sensor Signal Malfunction	Continues to control	After 5 seconds, returns both headlight swivel motors back to front
Height Control Sensor Signal Malfunction	Stops operation after returning to initial position (Fail at higher than initial position) Stops operation at current position (Fail at lower than initial position)	Returns both headlight swivel motors back to front
Headlight Leveling Motor Malfunction	Normal side headlight leveling motor Stops operation after returning to initial position (Fail at higher than initial position) Stops at current position (Fail at lower than initial position)	Returns both headlight swivel motors back to front
Headlight Leveling Motor Malfunction	Abnormal side headlight leveling motor Stops at current position	Returns both headlight swivel motors back to front
Communication Signal Malfunction	Skid control ECU Judges that vehicle speed is 0 km/h (0 mph) and continues control	Returns both headlight swivel motors back to front
Communication Signal Malfunction	Steering angle sensor Continues to control	Returns both headlight swivel motors back to front