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Home >> Toyota >> 2002 >> Sienna LE V6-3.0L (1MZ-FE) >> Repair and Diagnosis >> Relays and Modules >> Relays and Modules - Lighting and Horns >> Headlamp Control Module >> Description and Operation
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Headlamp Control Module: Description and Operation

SYSTEM OUTLINE

AUTOMATIC LIGHT CONTROL
When the light control SW is set at AUTO, the automatic light control system automatically turns on or off the taillights and headlights depending on the brightness around the vehicle.

AUTOMATIC LIGHT CONTROL OPERATION
The automatic light control sensor converts the intensity of the illumination into frequency and inputs it to the integration relay. When the light control SW is set at AUTO, the signal is input to TERMINAL (A) 8 of the integration relay, the taillights and headlights are automatically turned on or of.
- Turn on function
When the integration relay receives a frequency signal from the automatic light control sensor, and determines that the brightness around the vehicle is below a predetermined level, it controls the TERMINALS (A) 9 and (A) 11. This turns on the taillight relay and HEAD relay, and thus turns on the headlights and taillights.
- Turn off function
When the integration relay receivers a frequency signal from the automatic light control sensor, and determines that the brightness around the vehicle is above a predetermined level, it controls the TERMINALS (A) 9 and (A) 11. This turns off the taillight relay and HEAD relay, and thus turns off the headlights and taillights. In addition, the headlights and taillights will be turned off when the ignition SW is turned from on to off and the driver door is opened, during automatic light control.

LIGHT AUTO TURN OFF
With the ignition SW turned on, the current flows to TERMINAL 7 of the integration relay through GAUGE fuse. Voltage is applied at all times to the integration relay through the taillight relay (Coil side), and to the integration relay through the daytime running light relay (Main).

1. NORMAL LIGHTING OPERATION

With the light control SW turned to TAIL position, a signal is input into the integration relay. Accordingly, the current flows to the integration relay to TERMINAL 14 of the light control SW to TERMINAL 16 to GROUND, and taillight relay causes taillights to turn on.


With the light control SW turned to HEAD position, a signal is input into the integration relay. Accordingly, the current flows to the integration relay to TERMINAL 13 of the light control SW to TERMINAL 16 to GROUND in the headlight circuit, and the taillight relay and HEAD relay turn the lights on. The taillight circuit operation is same as above.

2. LIGHT AUTO TURN OFF OPERATION
With the lights on and the ignition SW turned off (Input signal goes to TERMINAL 7 of the integration relay), when the driver's door is opened (Input signal goes to TERMINAL 6 of the integration relay), the relay operates and the current which flows to the integration relay in the taillight circuit and the integration relay in the headlight circuit is cut off.
As a result, all lights are turned off automatically.
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