The radio key for the car
Here you will find useful information and valuable tips on all aspects of encoding car keys and programming hand-held radio transmitters.
Important safety note
The following technical information and practical tips have been compiled by HELLA in order to provide professional support to vehicle workshops in their day-to-day work. The information provided on this website is intended for use by suitably qualified personnel only.
Modern vehicle access systems consist of individually and compatibly programmed radio transmitter keys and receivers. An active button control on the remote control enables a range of comfort functions to be thus activated in the vehicle. The radio remote control signals are sent to the electronic control unit for access and ignition authorisation in the comfort system of the vehicle and are subsequently evaluated. If identification is positive, access to the vehicle is granted and the doors are unlocked. We would now like to take as an example the ignition key with the 3-button radio remote control (folding key) of the Volkswagen Group for the vehicle makes Skoda, Volkswagen and Seat. This vehicle key allows the vehicle to be opened and locked both mechanically and also via radio signals.
Together with the lower part of the key, the hand-held radio transmitter forms one unit to function as the ignition key for the vehicle in question. This lower part of the key houses the immobiliser transponder and the key bit. The vehicle can be opened mechanically with this key bit by using the door lock and it can also be started with the key bit via the ignition lock. The integrated transponder is required in order to deactivate the immobiliser before starting the engine.
The hand-held radio transmitter, which is also called the transmitting unit or radio element, serves the purpose of locking and unlocking the vehicle doors via the central locking system.
Depending on the vehicle model or on the country of registration, the design and the functions of the hand-held radio transmitter can vary.
In the case of European vehicles, hand-held radio transmitters normally use a frequency of 433 MHz or 434 MHz. On the American and the Asian markets the frequency 315 MHz is used.
A red emergency button integrated in the side of the housing can be used optionally but is country-specific. When this red button is operated, an acoustic and visible alarm is triggered on the vehicle, a feature which can be helpful in an emergency situation or also when trying to locate the vehicle in confusingly laid-out car parks.
If ever the vehicle battery is in a state of exhaustive discharge or the radio transmission is disrupted, the vehicle can be opened using the mechanical lock cylinder.
Unfold the key bit. Separate the lower section of the key from the hand-held radio transmitter. Place a screwdriver in the gap between the two halves of the housing and lever apart.
Position the key bit between the upper and lower part of the housing and lever apart.
Remove the battery from the housing. Insert new battery, ensure polarity is correct. Reassemble the vehicle key in reverse order.
When the button cells are inserted, care should be taken not to touch the two battery poles with the fingers at the same time. Together with humidity, this causes a short circuit and can considerably shorten the life of the battery. We recommend the use of plastic tweezers or the wearing of disposable gloves.
If an additional, new, hand-held radio transmitter is required or needed as a result of loss or a defect, then this transmitter has to be programmed or "taught" in the vehicle from scratch. All vehicle keys including hand-held radio transmitters and also a suitable diagnosic unit make up the equipment required for the carrying out of such programming or "teaching". All the hand-held radio transmitters that have already gone through the learning process for the vehicle will have their programs deleted by this new programming.
The learning process will now be illustrated by using the example of a mega macs 77 diagnostic unit.
Taking one vehicle key, separate the housing section with the key bit and the transponder from the hand-held radio transmitter. Place a screwdriver in the gap between the two halves of the housing and lever apart.
Enter vehicle data in the diagnostic unit. Connect the diagnostic unit with the on-board communication interface.
Insert the lower section of the housing with the key bit and the transponder in the ignition lock and switch on ignition. Then close the driver's door but leave the window open.
Within 15 seconds of this prompt, the unlock button on every key to be programmed has to be pressed one after the other (Picture 5).
The signal recognition and also the programming of each individual hand-held radio transmitter are then acknowledged by a quick flashing of the direction indicators (Picture 6).
After all the hand-held radio transmitters have been activated, input in the diagnostic unit has to be finally confirmed. When all input has been successfully completed, confirmation will be given by the diagnostic unit.
Following completion of programming, fit together all vehicle keys and check each one to see that all remote control key functions are in good working order.
Before being put into operation, the new hand-held radio transmitter has to be "taught" or programmed to suit the central locking system of the relevant vehicle. Whenever a hand-held radio transmitter is reordered, it is imperative to note the design, the number of control buttons, the transmission frequency and the LED position. Furthermore, every hand-held transmitter has an identification number, which should be used as a reference when searching for spare parts. A hand-held transmitter wrongly allocated to a vehicle cannot be programmed to suit that vehicle. With regard to this fact, please pay careful attention to the leaflet supplied with the product and also observe the programming notes issued by the vehicle manufacturers.
In this video we show you how to encode a car key or how to program a hand-held radio transmitter using the example of a VW Golf 5 Plus and a mega macs 77 diagnostic unit.