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Home >> Lexus >> 2000 >> SC 400 V8-4.0L (1UZ-FE) >> Repair and Diagnosis >> Relays and Modules >> Relays and Modules - Lighting and Horns >> Headlamp Control Module >> Description and Operation >> Automatic Light Control
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Automatic Light Control

With the ignition SW turned ON, current flows to TERMINAL 1 of the automatic light control sensor through ECU-IG fuse. Voltage is applied at all times to TERMINAL 6 of the automatic light control sensor through the taillight relay (Coil side). and to TERMINAL 5 of the sensor through the HEAD relay (Coil side).

AUTOMATIC LIGHT CONTROL
When the light control SW is in AUTO position, if the automatic light control sensor detects a decrease in the ambient light (To between 80 and 450 lux). The automatic light control sensor is activated. About 5 seconds after it is activated, current flows from TERMINAL 4 of the sensor to TERMINAL 12 of the light control SW to TERMINAL 4 to GROUND, lighting up the headlights and taillights.
If the ambient light drops bellow 80 lux, the automatic light control sensor is activated and about 3 seconds later current flows from TERMINAL 4 of the sensor to TERMINAL 12 of the light control SW to TERMINAL 4 to GROUND, lighting up the headlights and taillights.
When the light control SW is in AUTO position and activation of the automatic light control sensor has turned ON the headlights and taillights, if the automatic light control sensor detects the ambient light above 950 lux, the sensor is turned OFF after about 5 seconds. So the current from TERMINAL 4 of the sensor to TERMINAL 12 of the light control SW is cut off and the headlights and taillights turn OFF.