You first need to verify the integrity of the alarm keychain. The reason for its failure may be mechanical damage of the case: a chance to sit forgotten in the back pocket key chain or just drop it on the asphalt - and that the device is already no signs of life.
Damage can appear by themselves as a result of prolonged operation of the key FOB from the strong pressing of the Board elements are able to deform. To detect such defects can only open the case of the device.
The key chain can refuse to work even when intact - often the cause are just exhausted their supply of energy batteries. To verify this guess is simple: on the surface of the keyring need to find a led indicator that notifies that the device is functional. If the indicator is not lit, then it is time to replace the batteries.
Even new batteries can quickly come into disrepair, if you bought them in the cold - low temperature significantly reduces the service life. It is better to buy them in the store and not from street stalls, and to give preference to well-known brands.
The synchronization fails
Refusing to work may be the result of out-of-sync the FOB and alarm system. To restore the correct settings, you need to find a way to get inside the car and get to the special button "Valet", and then re-sync the key FOB. The necessary procedures differ depending on the type of alarm they are all listed in the user manual of your anti-theft system.
The so-called hang-up key chain is also able to interfere with its work. To solve such problems it is necessary to repeatedly press a button to activate the alarm, the device returned to service.
It may happen that the problem lies not in the key FOB that you use, and the Parking spot. Leaving the car next to offices of major companies, banks or government agencies you run the risk of spending a lot of time waiting for the moment when the key FOB will work again. All because of a special device, which are used for important negotiations to exclude the possibility of them listening. These devices create noise that interfere with the anti-theft alarm to receive the signal from your keychain. To overcome such interference does not work, so we'll just have to wait for their disappearance.