AUTO LIGHT SYSTEM OPERATION
id091800102100
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Note
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• 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).
• The auto light system receives a headlight illumination/off request signal from the auto light sensor and the auto light/wiper control module turns the headlights on and off.
• If the upward and forward illumination sensors detect the illumination level at which the headlights should be illuminated/turned off, the auto light sensor sends a headlight illumination/off request signal.
• If the auto light sensor detects that the vehicle is being driven at night after sending the headlight illumination request signal, it switches to the night mode and changes the headlight off conditions so that the headlights do not turn off and on repeatedly due to temporary brightness from street lights or store lighting, making it difficult for the headlights to turn off.
Night mode
• When the upward and forward illumination level sensors detect an illumination level of approx. 2,000 lux or less for approx. 10 min after sending the headlight illumination request signal, the auto light sensor determines that the vehicle is being driven at night and the auto light system is switched to the night mode.
• The auto light sensor determines the headlight off condition based on the average illumination level for the previous 3 min detected by the upward and forward illumination level sensors while in the night mode.
• If the average illumination level of the calculated past 3 min is approx. 4,000 lux or more, the auto light sensor cancels the night mode and sends a headlight off request signal.
• When a headlight switch OFF signal is input while in the night mode, the auto light sensor cancels the night mode.
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Caution
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• If the vehicle is driven a long-distance in a tunnel, the traffic is congested inside a tunnel, or the environment (temperature, buildings, tree shadows) surrounding the vehicle is dark for approx. 10 min, even if the surroundings are bright during daytime, the conditions for driving at night will be met and the auto light sensor may switch to the night mode.
• Because turning off of the headlights is determined by the average illumination level for the past 3 min when the mode is switched to the night mode during daytime while the surrounding area is bright, if the vehicle is driven in an environment (temperature, buildings, or tree shadows) surrounding the vehicle which is dark, the average illumination level may be insufficient and the condition for turning off the headlights may not be met, therefore the night mode may not cancel (headlights continue to illuminate).
Operation
Illumination condition
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• 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:
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― The forward and upward illumination level sensors detect approx. 2000 lux or less.
Lights off condition
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• When the light switch is in the AUTO position, the headlight and TNS turn off under the following conditions:
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― 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.
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.
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.
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
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Malfunctions
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Fail-safe function
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Recovery items
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Before operation
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After operation
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• Auto light sensor error
• Auto light sensor communication error
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Headlight illuminated
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Maintains headlights on
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• 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
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TNS illuminated
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Maintains TNS on
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Off
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Maintains turn-off
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