Adaptive Front Lighting System Module - Operation

OPERATION

The microprocessor in the Adaptive Front Lighting System (AFLS) module contains the logic circuits and controls all of the features of the AFLS. The AFLS module also controls the functions previously performed by the Automatic Headlamp Leveling Module (AHLM). The AFLS module uses On-Board Diagnostics (OBD) and communicates with other electronic modules in the vehicle as well as with a diagnostic scan tool using the Controller Area Network (CAN) data bus. The AFLS module is also a Local Interface Network (LIN) master node and uses this method of communication to communicate with the two stepper motors within each right and left front lamp unit.

The AFLS module microprocessor continuously monitors electronic message inputs from the Body Control Module (BCM) (also known as the Common Body Controller/CBC), the Integrated Center Stack (ICS), the Steering Angle Sensor (SAS), the Steering Control Module (SCM) and the Controller Antilock Brake (CAB) (also known as the Antilock Brake Module/ABM, the Antilock Brake System/ABS module or the Electronic Stability Control/ESC module). The AFLS module also energizes or de-energizes the front and rear axle sensors as appropriate to monitor the vehicle height. When the axle sensors are energized, the AFLS module monitors and evaluates the Pulse Width Modulated (PWM) return signals from those sensors.

The AFLS module uses these inputs to determine steering wheel angle, vehicle speed, accelerator pedal position, vehicle yaw rate and ABS status. It then uses internal programming algorithms to compute the proper electronic message control outputs to provide over the LIN bus to the LIN slave headlamp leveling and headlamp swiveling stepper motors to adjust the headlamp beams vertically or horizontally as required. The AFLS module also continuously monitors return inputs from the leveling and swiveling motors to confirm stepper motor responsiveness as well as the proper positioning of the headlamp beams.

The AFLS module receives battery voltage on a fused ignition switch output (RUN) circuit, and is grounded at all times through a hard wired remote ground point. These connections allow the AFLS module to operate only when the ignition switch is in the ON position. The AFLS module also monitors all of the AFLS circuits and components, then sets active and stored Diagnostic Trouble Codes (DTC) for any monitored system faults it detects.

The hard wired circuits of the AFLS module may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the AFLS module or the electronic controls or communication between modules and other devices that provide some features of the AFLS. The most reliable, efficient, and accurate means to diagnose the AFLS module or the electronic controls and communication related to AFLS operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.