How to Fix a Key Fob That isn't Working
If your key fob doesn't work, you can fix it with just a few steps. The first step is to be sure it's not the backup remote.
If the backup remote is able to lock and unlock your car doors it is most likely an issue with the main remote. The most common causes for car remote key failure are issues with the circuitry or battery.
Battery
The battery in the key fob may be worn out over time. It is relatively easy to replace batteries, but it is essential to ensure 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 require. It is also a good idea to examine the battery compartment carefully, as dead batteries sometimes leak harmful chemicals that can damage the remote. If changing the batteries does not solve the problem it could be that there are other issues that require professional attention. If buttons are damaged or stuck for instance it could be necessary to take the remote apart and rework each component. You could also try reprogramming the vehicle to recognize the new fob.
Buttons
From repeated use, key fobs could wear out and become dirty. This is not atypical, but it can cause buttons to stop functioning or require a difficult press to get them to work. This can be extremely frustrating especially if you're out of town and need to start your car. Even malfunctioning or worn-out buttons are often fixable with a little effort and materials you already have at home.
First, verify that the batteries are properly installed and that the indentation at the back of the button is filled. Then, carefully open up the remote and inspect the circuit board. Check for signs of corrosion or other indications that buttons are worn out or damaged, such as missing the conductive paint. Then, using 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 block the button from firing when it is pressed.
Examine the battery connector's terminals for loose solder connections. Soldering relevant website to their original position will restore the button's functionality If this is the case. You can follow the same method to restore functionality to any other loose connection within the fob.
If, for instance, any of the buttons made of rubber on the front of the key fob aren't working or require a very long press to function, it is likely that the graphite disks at the back of the button are deteriorating and require replacement. You can usually do this by rubbing a pencil over 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 could be that the circuitry is failing. This can be fixed with a quick clean and re-soldering, but it is best to have an extra fob available in the event this method does not work for you.
Circuitry
If the key fob buttons function, the circuit board inside your remote might be dirty. A thorough inspection is often enough to resolve this problem. The most frequent causes of dirty circuit boards is water and damaged cases. A broken case can allow water and other debris to enter the circuit board, causing it to short. Water can also damage pins and vias, which are tiny connectors on the board.
If you're able to remove your key fob and don't mind a little mess, we can de-solder the buttons and put new ones in their place. It's also worth examining the battery terminal connections. They can become very filthy and if they're not tight enough, the buttons may not work or even stay in their down position. Soldering the terminals and buttons back in place is usually all that's needed to return a non-working key fob to working order.
Non-Remote Transponder Chips
Sealed non-remote transponder chip are more durable than the remote fobs that contain them but they can be damaged by a hole that is that is drilled into them or over by a lawnmowers or car door handle. Failures of the fuse are typically to blame for non-remote chip failures.
If you're not comfortable opening the key fob, remove the circuitboard and utilize a multimeter to verify that the diode is functioning correctly. If you're not comfortable doing this, visit your local hardware store or Oreilly's and they usually have a RFID frequency tester that can tell you whether the key fob transmitting a signal.
Programming
Key fobs endure many abuses and aren't completely indestructible. They may lose their connection with the receiver in your vehicle due to shocks or a low battery, which calls for the reprogramming. A professional auto locksmith, or a dealer in the main can reprogram your keyfob to get it functioning again. In the rarer case that resetting or repairing your key fob doesn't work it could be the time to replace it completely.