How to Repair a Remote Key
While the majority of remote key fobs have excellent battery life, they'll eventually run out of battery. Some times it is as simple as changing the batteries in the device, however sometimes the problem can be more serious.
Remove the remote from the unit and clean the buttons. Then, flex them in and out. These techniques may be all that you need to get your key fob working properly.
Battery
Car key remotes use CR2025 or CR2032 batteries and can usually be replaced in the event that the device is functioning. If not, you can inspect the battery terminals or buttons to see if there are any loose parts. You can usually solder the terminals and buttons back into their original positions. However, keys repair will need to know what kind of battery is being used in your fob.
If the battery isn't the problem, try using an alternative key fob and see if you can unlock or start your car using it. If you can, then it's time to replace the primary fob. If it doesn't then you'll require a professional to inspect it to determine the issue. It could be as easy as reprogramming, or it could require other types of repair. It could also be that your vehicle has forgotten the fob. This isn't something you can fix on your own.
Case Study
The outer plastic housing of a remote is called the case. It usually comes with an alternative button pad. It is crucial to get a new case as the original will probably be pretty grungy and it is vital that the circuit board is installed properly in the case. The circuit board determines the function of the key fob. You can test it with a multimeter set to RF (radiofrequency) mode and a radio scanner that is tuned to the same frequency as the key fob.
Another thing to examine is the button contact points on the keypad, which could be loose or damaged in the course of time. By carefully re-soldering them back into place will often restore the functionality of the keypad unless they completely snap off.
Buttons
If the buttons on your key fob do not function anymore or are difficult to press for any reason, a motormite or dorman key housing replacement for your remote can be purchased for a low price online for your year/make and model. Then, simply pop the circuit board out of your old case into the new. You may have to slightly adjust the position of your circuit board for certain models. You can then apply aluminum foil and double-sided tape to stick to the black contact points on the buttons.
Programming
The key fob and the receiver in your car are paired however, this connection may be ruined. A professional will assess your car to determine the year, make and model. They will then use special equipment to reconnect or program a blank transponder chip or fob (or clone the key, if possible). They will then test the remote to confirm that it works.
When reprogramming keys that are blank it is crucial to take care. The process is complicated and each manufacturer offers distinct instructions. It is also possible to miss a step or take too long to exit the programming mode, so it is best to use a professional with comprehensive knowledge of your car's security system to reduce the chance of damaging your car. Certain programming tools can also be capable of analyzing diagnostic trouble codes from your vehicle, which could help repair or troubleshoot other problems.