Headlamp Leveling/Adaptive Forward Lighting Control Block Diagram

Fig 1: Headlamp Leveling/Adaptive Forward Lighting Control Block Diagram

Courtesy of GENERAL MOTORS COMPANY

Automatic Headlamp Leveling (without Electronic Suspension Control) 

The automatic headlamp leveling system automatically maintains the vertical alignment of the headlamps when the vehicle load and driving conditions change. Each headlamp assembly contains a headlamp leveling motor that is controlled by the headlamp control module. The front and rear suspension position sensors provide the headlamp control module with suspension position information. Each sensor receives a 5 V reference, signal and low reference circuits from the headlamp control module. The sensors are connected to the control arms of the front and rear suspension. As the vehicle travels, the suspension compresses and rebounds moving the suspension position sensor arms. This causes the signal output of the sensor to change. The headlamp control module compares the information from both suspension position sensors and adjusts the headlamp leveling as needed.

Automatic Headlamp Leveling (with Electronic Suspension Control) 

Each headlamp assembly contains a headlamp leveling actuator that is controlled by the headlamp control module. The front and rear suspension position sensors provide the suspension control module with suspension position information. Each sensor receives a 5 V reference, signal, and low reference circuits from the suspension control module. The suspension position sensors are connected to each control arm of the front and rear suspensions. As the vehicle travels, the suspension compresses and rebounds moving the suspension position sensor arms. This causes the signal output of the sensor to change. The suspension control module compares the information from all four suspension position sensors and adjusts the suspension as needed. The suspension control module communicates with the headlamp control module via serial data. The headlamp control module uses the suspension position sensor information received from the suspension control module to adjust the headlamp leveling as needed. The headlamp control module communicates with the left and right headlamp leveling actuators via the LIN serial data circuit.