Keyless Entry System - E-Class & C-Class: Operation: Function

The infrared remote control can only be operated with transmitter for vehicle, transmitter and control module installed in vehicle are matched to one another.

Transmitter transfers signal to receiver in form of an infrared beam. After receiving light beam, receiver filters out extraneous light, amplifies signal and transfers it on to control module via a control line.

Remote control signal consists of a fixed code which is coded again by a processor. This additional coding changes each time it is actuated. This makes it impossible to decode remote control signal.

Control module decodes remote control signal and, when fixed code is correct, actuates central locking, convenience feature and Anti Theft Alarm. Simultaneously infrared control module sets itself for next remote control signal locking out previous remote control signal.

If remote control is actuated outside of reception range, current remote control signal changes in remote control, however not in control module. When remote control is used again in reception range, remote control signal from remote control no longer coincides with signal expected by control module. However, since control module can calculate next 250 switching operations, it automatically sets itself to current remote control signal.

If remote control is actuated more than 250 times outside of reception range, it is necessary to synchronize remote control. See SYNCHRONIZING INFRARED REMOTE CONTROL SIGNAL  under PROGRAMMING.

If a remote control key is lost, alternating code portion of remote control signal can be reset (desynchronized) by connecting terminal 31 on RCL diagnostic connection to data link connector X11/4 for 30-40 seconds with ignition ON.