GDL-Master And GDL-Slave: Notes
There are two Gas Discharge Lamp Modules (GDLs), one for each headlamp. The one located on the driver's side of the vehicle acts as "master" and communicates with the Central electronic module (CEM) via LIN-communication. The other Gas Discharge Lamp Module (GDL)acts as "slave" and communicates with the "master" control module via LIN-communication.
Other information
An electronic ballast is connected to each headlight. The ballast acts as a voltage regulator and generates alternating voltage (AC).