If it is not programmed (via STAR) it will cause it to run much longer than necessary and will burn up the motor!!! Also without programming some options in your car may not work properly. One common option is Trunk Assist Soft Close. This will not work if not programmed. Note If you need access to Mercedes diagnostic software.
An inexpensive option is Mercedes Xentry Pass thru. All you need is a laptop the software and a usb cable. (only need one cable) with it you can program the pump.