How to Fix a Key Fob That isn't Working
If your key fob doesn't work, you can fix it by following some simple steps. The first step is to be sure it's not the backup remote.
If your backup remote is unable to unlock and lock the doors of your car, it is likely that the primary remote isn't functioning. Most car remote key failures are caused by circuitry or battery issues.
Battery
It is not uncommon for the battery in a key fob for cars to wear out. It is relatively easy to replace the battery, however it is crucial to ensure that you use the right type; you can look in your owner's manual, or contact the dealer for the manufacturer to find out the kind of battery you require. It is also crucial to inspect the battery compartment as batteries that are not working properly can release toxic chemicals that could damage the remote. If changing the battery doesn't solve the issue, there may be other issues requiring professional attention. If buttons are damaged or stuck for instance it could be necessary to take the remote apart and rework each component. You can also try reprogramming the vehicle to recognize the new device.
Buttons
Key fobs can get dirty and worn out from frequent use. It is not uncommon to have buttons stop functioning, or require a long push to make them work. This can be a hassle, especially when you are away from your home and have to start your car. Fortunately, even worn-out or broken buttons can usually be fixed with a bit of time and a few items you have in the home.
First, check that the batteries are up correctly and that the indentation on the back of the button is filled. Then, open the remote with care and look over the circuit board. Check for signs of corrosion or other signs that the buttons are worn out or damaged, such as missing conductive paint. Use a Q-tip that has been dipped in alcohol to gently clean any membrane contact that has worn out or where conductive painting is missing. Don't rub too hard in order to damage the conductive paint and prevent the button from firing when pressed.
Also, be sure to check the battery connector's terminals for a loose solder connection. If this is the case, soldering them back in place could restore function to the button. You can use the same procedure to restore functionality to any other loose connection within the fob.
If any of the rubber buttons located at the front of the keyfob are not working or need to be press very hard, the graphite disks at the back of the button could have worn out and will require replacement. It is usually done 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 are unable to get the button to respond when pressed hard, it is possible that the circuitry has failed. It is possible to fix this by cleaning and re-soldering your fob but you should also have an extra in case it does not work.
Circuitry
If the key fob buttons are working the circuit board in the remote could be dirty. The issue can be solved by a thorough inspection. source web page for dirty circuit boards are water and damaged cases. A damaged case allows water and other debris to pass through and short out the electronics. Water can also eat away at pins and small connectors on the board, referred to as via's.
If you're handy enough to remove your key fob, and you're not afraid of some mess, we can de-solder the buttons and solder new ones in their place. It's also worth checking the battery terminal connections. If they're loose, the buttons could not function or get stuck in their down position. Soldering the terminals back into place is usually enough to return a malfunctioning fob to working.
Non-Remote Transponder Chips
The non-remote chips sealed in a sealed case are more durable than remote fobs, however they are susceptible to breaking if a hole is drilled in them or if a car door handle or lawnmower runs over them. Most of the time non-remote transponder chip malfunctions can be attributed to blowing fuses.
If you are not comfortable opening the key fob, you can remove the circuitboard and utilize a multimeter to verify that the diode is operating properly. If you don't feel comfortable with this, you can go to your local Oreilly or hardware store and use their RF frequency tester. This will let you know whether the key fob transmits an RF signal.
Programming
Key fobs aren't indestructible and can be damaged by a lot of things. They can lose their pairing with the receiver inside your vehicle due to shocks or a low battery, requiring changing the program. A professional auto locksmith or main dealer can reprogram your key fob to get it back up and running. If resetting or replacing your key fob fails it is possible to replace it.