Automatic Headlight Beam Level Control: Notes
The automatic headlight beam level control system regulates the orientation of the reflectors of the headlights in relation to the posture of the vehicle that has been detected by sensors. See Fig 1. Thus, it is a system that maintains the headlight beams to a constant level while the vehicle is being driven.
The headlight beam level control ECU assessed the vehicle's posture through the signals from the rear height control sensor. There is another piece of information that is used for assessing the vehicle's posture. It also determines whether or not the front passenger seat is occupied. This is accomplished by way of the ON/OFF signal of the occupant detection sensor, which is built into the front passenger seat and the seat belt buckle switch.
The headlight beam level control ECU has the initial value of the rear height control sensor stored in it's memory. Therefore, if a repair that alters the output value of the rear height control sensor has been performed (such as removal and reinstallation of the rear height control sensor or the suspension), it is necessary to initialize the sensor and adjust the beams.