What is a Mercedes Benz key made up of?

This blog will help you understand the key components of a Mercedes Benz key and help you unlock its true potential. The answers to the following questions are also present in the blog: can you make a duplicate Mercedes Benz key? How does a Mercedes Key work? What to do if the Mercedes Benz Key is inoperative?

What is a Mercedes Benz key made up of?

The Mercedes Benz Key is made up of the following components:

  • Radio antenna
  • Receiver antenna
  • Integrated circuit and battery

The function and role of each component are explained below:

  • Radio antenna

When the key is pressed, it is designed to send signals to the vehicle via radio waves. A signal transmitter antenna is built into the key. The range of the transmitter antenna is limited because of the size and power available in the key.

 Ideally, the range of the key can be up to 20 metres from the vehicle but if there are objects in between the key and the vehicle then the range is reduced to 5-10 metres.

Some of the old models used an infrared transmitter in the key that sends data to the infrared receiver usually located in the driver’s side door or the inside rear view mirror. This technology discontinued the introduction of the third-generation in-drive authorization system.

  • Receiver antenna

In Mercedes Benz models with keyless go or keyless start systems, there is a dedicated receiver antenna. The receiver antenna is tasked with receiving the wake-up signal for any of the keyless go antennas on the vehicle. 

The keyless go systems use additional keyless go antennas and a dedicated control unit connected to the electronic ignition lock via the controller area network data bus.

The keyless go antennas located on either side of the vehicle are constantly scanning for the vehicle’s key. The effective range is 2 metres and once the key is detected within the range it can lock or unlock the vehicle.

  • Integrated circuit and battery

The antennas are controlled by an integrated circuit made up of semiconductors and microcontrollers. To power the electrical circuit there is a DC battery in the key fob. 

old Mercedes Benz models used two batteries in the key as a single battery used to get discharged quickly. The latest models are back to a single battery as the microcontroller is programmed to put the key in battery-saving mode if it is outside of the activation range.

The battery voltage can be up to 5 volts and Mercedes Benz sells key batteries in case the original battery is discharged. The key has an independent battery tray that can be accessed by opening the back cover on the key. 

The keyless go keys are only applicable to models with the remote start/stop function and the cost of the key is more than the standard key. A standard key only uses a radio transmitter and is incapable of receiving any wake-up signals.

Can you make a duplicate Mercedes Benz key?

It is not possible to create a duplicate Mercedes Benz Key from an original key. Mercedes Benz dealerships give two choices, it is possible to get a replacement key for your original key or they can programme an additional key. 

Due to the way the drive authorization system is designed in Mercedes Benz models, it is not possible to have two functional duplicate keys at the same time. 

As soon as the replacement key is paired to the vehicle the old key will become inoperative. This is a good security feature as unauthorised access to the vehicle can be prevented with the lost or a stolen key. 

Dealerships also have the necessary tools to block the key temporarily in case the customer requires time to find it.

The programming of the key needs a special device called a key station, which is similar to the electronic ignition lock control unit. A blank key is inserted into the machine and programming is performed according to the vehicle-specific data.

There are two different part numbers for the blank key. If the vehicle is equipped with keyless go systems then the cost of the blank key is slightly more expensive than the cost of a standard key. If the standard key is used in a keyless go system then it will not start the vehicle as there is no receiver antenna built into the key.

The mechanical key is used to open the driver’s side door only in emergencies like an inoperative key, low key battery and if the key is locked inside. A duplicate mechanical key can be purchased from the authorised dealership after verifying the vehicle documents and customer details.

How does a Mercedes Key work?

A Mercedes Benz key has a built-in battery to send and receive data from the electronic ignition lock control unit. When the key is actuated, a radio signal is received by an FM amplifier located near the rear windshield of the vehicle.

The FM amplifiers verify the key identification number, if the key belongs to the vehicle only then it will transfer it to either a keyless Go control unit or rear signal actuation and acquisition control unit. These control units are connected to the electric ignition lock over the CAN bus data network. 

The electronic ignition locks receive the data from the key and driver authorization is verified. There are two codes transmitted by the key, one is used to gain access to the vehicle and another is for starting it.

What to do if a Mercedes Benz key is inoperative?

If a Mercedes Benz key is inoperative and the spare key is not present then perform the following steps:

  • Press the switch on the back side of the key and pull out the mechanical key.
  • Use the mechanical key to remove the protective cover on the door handle and insert the key into the door lock.
  • A mechanical key will unlock the driver-side door, after gaining access to the vehicle put the mechanical key back in the key fob.
  • The start-stop switch on models produced before 2016 is removable and after removing it reveals a key slot to insert the key.
  • On models produced after 2016, place the key in a marked space message that will appear on the instrument cluster.
  • The market space is in the centre console and there is a special antenna with an inductive coil which will temporarily power the key and extract the drive authorization codes. The antenna is also connected directly to the electronic ignition lock control unit.

Other articles about Mercedes Benz you may be interested in

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Mercedes Benz keys are advanced and offer various functions like comfort opening and comfort closing, global and selective vehicle lock and unlock. Therefore, they are made up of various components. The material itself is also durable and rubber gaskets are installed to keep the moisture away from the electric circuits.