How to Fix a Key Fob That isn't Working
If your key fob doesn't work, a few easy steps can be taken to fix it. The first step is to be sure that it's not the backup remote.
If your backup remote can lock and unlock the doors of your car, it is likely that the main remote isn't functioning. The most common causes for key problems with your car remote are battery or circuitry issues.
Battery
It is not unusual for the battery in a car key fob to degrade. It is easy to replace the battery. However it is crucial that you use the correct kind. You can refer to your owner's manual or call the manufacturer to determine the right kind. It's recommended to examine the battery compartment with care because dead batteries can leak harmful chemicals that can damage the remote. If replacing the batteries doesn't solve the issue, it may be that there are other issues that require attention from a professional. For example, if buttons appear stuck or damaged it could be necessary to disassemble the remote and rework its components. You can also try reprogramming your car to recognize the new key fob.
Buttons
Through repeated use, key fobs can become worn and dirty. It is not common to have buttons stop working, or to require a long press to get them working. This can be frustrating especially when you're away from home and need to start your car. Fortunately, even worn out or broken buttons can usually be fixed with just a bit of time and some of the materials you have in the house.
First, check that the batteries are properly charged and that the indentation on the back of the button is filled. Then, open the remote with care and look over the circuit board. Look for nearby key repair shop of corrosion or other indications that the buttons are worn or damaged, like missing the conductive paint. Use the Q-tip, dipped in rubbing alcohol, gently clean any membrane contacts that have become damaged or where conductive paint is missing. Avoid rubbing too hard, since this could cause damage to the conductive painting and prevent the button firing when it is pressed.
Also, make sure to inspect the battery connector terminals for an unattached solder connection. If this is the case, connecting them back could restore function to the button. You can follow the same procedure to restore functionality to any other loose connection inside the fob.
If any of the rubber buttons located at the front of the keyfob isn't functioning or require to be pressing extremely hard the graphite disks at the back of the button might have worn out and need to replaced. You can do this by rubbing a pen across the disks. This should bring the button back to life.
If none of these solutions work, or if you still cannot get the button to respond when pressed hard, it is possible that the circuitry has failed. It is possible to fix the issue by cleaning and re-soldering the fob, but you should have an extra in case it doesn't work.
Circuitry
The circuit board inside the remote control could be dirty regardless of whether the buttons on the key fob function or not. A thorough inspection will usually resolve this problem. Broken and damaged cases are the most common causes of boards that are dirty. A damaged case can allow water and other debris to pass through and short out the electronics. Water can also damage pins and small connectors on the board, which are known as via's.
If you are handy enough to open your key fob, and aren't afraid of making some mess, we can remove the buttons from their sockets and solder in new ones. It's also worth looking at the battery terminal connections. If they're loose, the buttons may not work or even become stuck in their down position. Soldering the terminals and buttons to their original positions is often enough to return a malfunctioning fob to a working condition.
Non-Remote transponder chips
Sealed non-remote transponder chip are more durable than remote fobs that contain them but they can be damaged by a hole that is drilled into them or run over by a lawnmower or door handle for a car. The failure of the fuse is usually the cause of non-remote chip failures.
If you're not confident opening the key fob, you may remove the circuitboard and utilize a multimeter to check that the diode is operating properly. If you're not sure with this, visit your local Oreilly or hardware store and use their RF frequency tester. This will tell you whether the key fob sends an RF signal.
Programming
Key fobs aren't impervious to destruction and are susceptible to damage by a variety of factors. They can lose their pairing to the receiver in your car due to shock or a low battery, which requires the reprogramming. A professional auto locksmith, or the main dealer, can reprogram your keyfob to get it functioning again. If, in the unlikely event that resetting or repairing your key fob fails it could be the time to replace it all over again.