Mercedes
Benz factory four door keyless entry

The original four door comfortable entry system includes: door wiring
harness, four door sensing handle, door high-frequency antenna, handle
buckle, high-end control unit, body wiring harness, and more.
What is a Comfort Entry System? Comfortable entry, also known as keyless
entry, is mainly used to sense the vehicle by carrying the key with you,
approaching the vehicle, and approaching the door without changing the
original car key. After the induction occurs, the car owner only needs to
reach into the unlocking induction area, and the car door will automatically
unlock (at the same time, the emergency light will flash once), and the car
owner can open the door and enter the car! On the contrary, after turning off
the engine and getting off the car, simply reach out and touch the lock
sensing area, and the car door will automatically lock (while the emergency
light will also flash once).