Operation

OPERATION

The xenon lamp module operates on battery current and ground received directly from the Body Control Module (BCM) (also known as the Signal Acquisition and Actuation Module/SAM). Each xenon lamp module controls operation of the xenon lamp, the electromechanical shutter that switches the xenon lamp between low and high beam as well as the operation of the cornering lamp. The BCM monitors direct inputs from the headlamp switch (also known as the Rotary Light Switch/RLS or light switch module) and electronic message requests received from the Roof Control Module (RCM) (also known as the Overhead Control Panel/OCP control unit or DBE) based upon rain/light sensor outputs to determine the proper control outputs to the xenon lamp module, which then provides a controlled voltage to operate the xenon lamp igniter as appropriate.

The BCM monitors electronic message requests from the Steering Control Module (SCM) (also known as the steering column module/MRM) based upon multi-function switch (also known as combination switch) outputs to determine the proper control outputs to the xenon lamp module, which then provides operation of the electromechanical shutter which determines the selected low or high beam xenon lamp output. In vehicles where the cornering lamp feature is enabled, the BCM also monitors electronic message requests from the SCM based upon multi-function switch and Steering Angle Sensor (SAS) outputs to determine the proper control outputs to the xenon lamp module, which then provides the appropriate cornering lamp operation.

The xenon lamp module includes pass-through circuits that control operation of the headlamp leveling motor based upon a direct input from the Automatic Headlamp Leveling Module (AHLM) (also known as the Adaptive Lighting, Headlamp Range Adjustment/HRA or LWR module), which monitors front and rear axle sensor outputs.

The hard wired xenon lamp module circuits may be diagnosed using conventional diagnostic tools and procedures. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the xenon lamp module or the electronic controls and communication that provide some features of the xenon lamp system. Proper diagnosis of the xenon lamp module, the BCM, the CAN data bus and the electronic communication related to xenon lamp module operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.