Automatic Headlight Beam Level Control: Operation

WARNING: This page is about a different car, the 2002 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.

While the vehicle is being driven, the rear height control sensor detects the vehicle's posture that varies in accordance with the road conditions or driving conditions. The resultant signals are then output to the headlight beam level control ECU. Based on these signals from the sensor, the ECU assesses the vehicle's posture. If the front passenger seat is occupied, as determined by the ON/OFF signals from the occupant detection sensor that is built into the front passenger seat and the seat belt buckle switch, control is effected by making a correction to the vehicle posture information provided by the rear height control sensor. In addition, the skid control ECU sends the vehicle speed signal to the headlight beam level control ECU, allowing the ECU to determine the vehicle's driving conditions. This ECU controls the actuator so as to cancel out the changes in the light beams that are caused by these changes in the vehicle's posture and speed.