AUTO LIGHT SYSTEM OPERATION

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

Operation


Illumination condition

•  When the ignition switch is turned to the ON position 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. 2000 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. 4000 lux or more for approx. 1.0 s.
―  The ignition switch is off.
―  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 sensors in the auto light sensor (installed in the windshield) detect the illumination level above and in front of the vehicle.

2.  If the upward or forward illumination sensors detect approx. 2000 lux or less in front of and above the vehicle, the headlight and TNS illumination control signal is sent to the auto light/wiper control module.

3.  The microcomputer in the auto light/wiper control module receives the control signal and sends current (1) to transistor A, causing the transistor A to turn on.

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

5.  The microcomputer in the auto light/wiper control module receives the control signal and sends current (2) to transistor B, causing the transistor B to turn on.

6.  When transistor B turns on, the headlight relay (LO) also turns on. At the same time, the headlights (low-beam) illuminate.

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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 above and in front of the vehicle.

2.  If the upward and forward illumination level sensor detect approx. 4000 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 auto light/wiper control module.

3.  The microcomputer in the auto light/wiper control module receives the control signal and turns off the current to transistor A, causing the TNS relay to also turn off.

4.  When the TNS relay turns off, the TNS also turns off.

5.  The microcomputer in the auto light/wiper control module receives the control signal and turns off the current to transistor B, causing the headlight relay (LO) to also turn off.

6.  When the headlight relay (LO) turns off, the headlights (low-beam) also turn off.

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Fail-Safe Function

•  When a auto light sensor malfunction or a communication error between the auto light sensor and auto light/wiper control module is detected, the auto light/wiper control module initiates controls as indicated in the fail safe function table.

Fail-Safe Function Table

Malfunctions
Fail-safe function
Recovery items
Before operation
After operation
•  auto light sensor error
•  auto light sensor communication error
Headlight illuminated
Maintains headlights on
•  Ignition switch lock position
•  When a auto light sensor malfunction is cleared
•  When communication is restored
•  When the light switch is in a position other than AUTO
TNS illuminated
Maintains TNS on
Off
Maintains turn-off