How to Fix a Key Fob That isn't Working
If your key fob won't work then you can fix it with a few simple steps. First, check to make sure it's not the backup remote.
If your backup remote can unlock and lock the doors of your vehicle, it is most likely that the primary remote is not working. The most common causes for key malfunctions for car remotes are battery or circuitry issues.
Battery
It is not uncommon for the battery in the key fob for cars to wear out. It is quite simple to replace the battery, however it is crucial to make sure that you use the right type and you can consult your owner's manual, or contact the dealer for the manufacturer to determine the type of battery you need. It is also crucial to check the battery compartment, since batteries that are not working properly can release toxic chemicals that could damage the remote. If changing the battery doesn't fix the problem there may be additional issues that require attention from a professional. For example, if buttons seem stuck or broken it could be necessary to take the remote apart and rework its parts. You could also try reprogramming the vehicle to recognize the new key fob.
Buttons
Through frequent use, key fobs can get dirty and worn. It is not uncommon for buttons to stop working, or to require a long push to make them work. This can be a huge hassle especially if you're out of town and need to start your car. Even malfunctioning or worn-out buttons can be fixed with a little time and materials you already have at home.
First, make sure that the batteries are correctly placed and that the indentation at the back of the button is filled. Take the remote apart and examine the circuit board. Look for signs of rust or other indications that the buttons have been damaged or worn out. For example, conductive paint may be missing. Utilizing a Q-tip that has been dipped in rubbing alcohol, gently clean any membrane contacts that have worn or have conductive paint missing. Don't rub too hard in order to damage the conductive paint and stop the button from firing when it is pressed.
Also, be sure to check the battery connector's terminals to ensure any loose solder connections. If this is the case, simply soldering them back in place may restore functionality to the button. You can follow the same process to restore functionality to any other loose connection within the fob.
If any of the rubber buttons located at the front of the keyfob isn't working or need to be pressed very hard, the graphite disks at the back of the button might have worn out and need to replaced. It is usually done by rubbing a pen over the disks. This will bring the button back to life.
If all of this doesn't help, or if the button does not respond to a hard push It could be because the circuit board has become damaged. It is possible to fix this by cleaning and re-soldering the fob, but you should have a spare in case it doesn't work.
Circuitry
Whether or not the keys fob buttons are functioning the circuit board that is inside your remote might be dirty. This issue can be fixed by a thorough inspection. The most common causes for dirty circuit boards are water and broken cases. A damaged case allows water and other debris to pass through and short out the electronic components. Water can also eat through pins and vias, which are small connectors that are found on the board.
If you are handy enough to open your key fob, and aren't afraid of making some mess, we can take the buttons out of their sockets and put in new ones. Also, you should check the connections between battery terminals. If they are loose, the buttons may not function properly or become stuck in their down position. Soldering the terminals and buttons back in their place is generally all it takes to restore keys that are not in functioning condition.
G28CarKeys -Remote Transponder Chips
Sealed non-remote transponder chips are more durable than the remote fobs that contain them but they can still be broken by a hole being made in them or pushed over by a lawnmower or door handle for a car. The failure of the fuse is usually to blame for non-remote chip failures.
If you're able to open a key fob that is sealed and can tolerate the mess, you can remove the circuit board and examine the fuse with a multimeter for proper diode function. If you're not sure with this, you can go to your local Oreilly or hardware store and utilize their RF frequency tester. This will inform you whether the key fob transmits an RF signal.
Programming
Key fobs endure a lot of abuse and aren't impervious to damage. They may lose their connection to the car's receiver because of shock or a low battery, requiring them to be reprogrammed. A professional auto locksmith, or main dealer can reprogram the keyfob and get it up and running again. In the rarer case that resetting or repairing your key fob isn't working it may be time to replace it all over again.