Remote Key
The remote key has a different number of buttons depending on the configuration of the vehicle. The information button is only found on vehicles with the keyless function installed. The remote keys differ in design depending on whether it contains the function for keyless entry of not. All remote keys contain a key blade. The key blade is normally retracted inside the remote key. The blade is used as a standby option to open the vehicle should there be a fault in the electric central locking system.
The buttons on the remote key are:
- Button to lock the vehicle
- Button to unlock the vehicle
- A button to unlock the trunk lid/tailgate
- A button to activate the vehicle lighting for 30 seconds
- Button to activate the vehicle's horn (only vehicles with alarms)
- Button to activate the heartbeat sensor and status check (only vehicles with keyless function installed)
The remote key, regarding internal design, consists of three sections:
- Transponder
- Circuit for remote control
- Circuit for keyless functionality.
The transponder is used so that the immobilizer system can identify the remote key when it is inserted in the Start control module (SCU). The transponder contains a unique code. The central electronic module (CEM) must be programmed with the transponder code before the vehicle can be started.
The circuit for remote control is used to lock and unlock the central locking and to activate the above functions. The circuits in the remote key that control the functionality are coded. These codes must be programmed into the Central electronic module (CEM) (vehicles without keyless function) or the Keyless vehicle module (KVM) (vehicles with keyless function) for communication to work.
The circuit for keyless functionality is used for:
- Unlocking
- Locking
- Passive starting
The circuits in the remote key which control the function for the keyless entry system are coded. The keyless vehicle module (KVM) must learn these codes for communication to function.
The remote key is powered by an internal button battery. The battery is used each time a remote key needs to communicate with the system via the remote control or keyless function. The battery is not used during communication with the key transponder when the remote key is in the start control module (SCU). The battery must be replaced at regular intervals depending on how often the remote key is used. The remote key contains an internal voltmeter that measures the voltage of the internal battery. If the battery's voltage becomes too low, the information about this is transmitted in the messages to the Remote Receiver Module (RRX). The Central electronic module (CEM) or Keyless vehicle module (KVM) (only vehicles with keyless function) receives the information and transmits a message via the CAN network to the Driver information module (DIM), which shows a message that the voltage is too low. Reduced remote key range is also an indication that the battery charge is low.
- Only applies to vehicles with the system for keyless function installed: If a button on the remote key is pressed when identifying the remote key, identification will fail. This is because the remote key cannot transmit and receive data at the same time (when a button is pressed in on the remote key it is busy transmitting "normal" remote control commands). This fault can occur if the remote key is in a pocket or a bag and a button is pressed accidentally.
- Due to increased ambient radiation, for example, from TV/radio transmitters and mobile phones, the signal from the remote key can, in some cases, be interrupted. Examples of sources of interference can be: wireless headsets, remote controls for other vehicles and manufacturers, remote controlled garage door openers, meters with remote reading and wireless weather stations. Radio waves from all these sources can create an area where all wireless communication, in principle, is impossible. In many cases this occurs, in certain locations, where different outside signals make transmission and reception conditions unfavorable. This affects not only remote control functions but all types of wireless communication.