AUTO LIGHT SYSTEM OPERATION


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Note
•  The illumination intensity at which the auto light system operates is approximate and for reference purposes. It varies depending on conditions in the surrounding area (weather, reflection off buildings).

Operation


Illumination condition

•  When the ignition is switched to ON and the light switch is in the AUTO position, the headlight and tail number side lights (TNS) illuminate under the following condition:
―  The forward and upward illumination level sensors detect approx. 2,000 lux or less.


Lights off condition

•  When the light switch is in the AUTO position, the headlight and TNS turn off under the following conditions:
―  The forward and upward illumination level sensors detect approx. 4,000 lux or more for approx. 1.0 s.
―  The ignition switch is turned to the ACC or LOCK position.
―  The light switch is in the OFF position.
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Illumination operation

1.  When the light switch is in the AUTO position, the illumination level sensors in the auto light sensor (installed in windshield) detect the illumination level above and in front of the vehicle.

2.  If the illumination level sensor detects approx. 2,000 lux or less, a TNS on control signal is sent to the body control module (BCM).

3.  When the microcomputer in the BCM receives the control signal, current (1) flows and transistor A is turned on.

4.  When transistor A turns on, the TNS relay turns on. At the same time the TNS illuminate.

5.  When the microcomputer in the BCM receives the control signal, current (2) flows and transistor B is turned on.

6.  When the transistor turns on, the headlight relay turns on. At the same time the headlights (LO) illuminate.


2-Beam Type

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4-Beam Type

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Lights off operation

1.  When the light switch is in the AUTO position, the illumination level sensors in the auto light sensor (installed in the windshield) detect the illumination level.

2.  If the upward and forward illumination level sensor detect approx. 4,000 lux or more for 1.0 s in front of and above the vehicle, the headlight and TNS off control signal is sent to the BCM.

3.  The microcomputer in the BCM receives the control signal and turns off the current to transistor A, causing the headlight relay to turn off.

4.  When the headlight relay turns off, the headlights (LO) turn off.

5.  The microcomputer in the BCM receives the control signal and turns off the current to transistor B, causing the TNS relay to turn off.

6.  When the TNS relay turns off, the TNS turn off.


Fail-safe function

•  When an auto-light sensor malfunction or auto-light sensor communication error is detected, the BCM initiates controls as indicated in the fail-safe function table.

FAIL-SAFE FUNCTION TABLE

Malfunction
Fail-safe function
Recovery condition
Before operation
After operation
•  Auto-light sensor malfunction
•  Auto-light sensor communication error
Headlights on
Headlights remain on
•  Ignition switch is turned off
•  Auto-light sensor malfunction is not detected
•  Communication is restored
•  Light switch is turned to a position other than AUTO
TNS on
TNS remain on
OFF (lights off)
Lights remain off