How to Fix a Key Fob That isn't Working
If your key fob isn't functioning A few easy steps can fix it. The first step is to be sure it's not the backup remote.
If the backup is able to lock and unlock your car door, then there's a likely issue with the primary remote. The most frequent causes of car remote key failure are circuitry or battery issues.
Battery
It is not uncommon for the battery inside the car key fob to wear out. It is fairly easy to replace the battery, however it is important to ensure that you select the correct one; you can look in the owner's manual or talk to the manufacturer's dealer to find out the kind of battery you need. It is also crucial to examine the battery compartment as batteries that are not working properly can release caustic chemicals that can harm the remote. If replacing the batteries doesn't solve the issue it could be that there are other issues that require attention by a professional. For example, if buttons appear stuck or broken it could be necessary to take the remote apart and rebuild its components. It is also possible to reprogramme the vehicle to recognize the new fob.
Buttons
Key fobs can get filthy and worn out due to repeated use. This is not atypical however it can cause buttons to cease working or require a long press to work. This can be frustrating, especially when you are away from your home and need to switch on your car. Even malfunctioning or worn-out buttons can be fixed with a little time and the tools you already have at home.
First, verify that the batteries are properly placed and that the indentation on the back of the button has been filled. Open the remote carefully and examine the circuit board. Check for evidence of rust, or other signs the buttons have been damaged or worn. For remote key fob repair that conducts electricity could be missing. Use a Q-tip dipped into rubbing alcohol to gently clean any membrane contact that has become damaged or where conductive painting is missing. Do not rub too vigorously, as this could erode the conductive paint, and block the button from firing when it is pressed.
Also, carefully check the battery connector's terminals to ensure a loose solder connection. If this is the case, soldering them back in place may restore functionality to the button. The same procedure can be used to restore function to any other loose connections within the fob.
If any of the rubber buttons on the front of the keyfob isn't working or require being press extremely hard, the graphite disks at the back of the button might have worn out and will require replacement. This can usually be done by rubbing a pencil on the disks, which should bring the button back to its original state.
If none of these solutions work or you not be able to get the button respond when you press it hard, it could be that the circuitry has failed. It is possible to fix this issue by cleaning and re-soldering your fob however, you should have a spare in case it does not work.
Circuitry
If the key fob buttons function the circuit board in the remote could be dirty. A very thorough inspection is often enough to resolve this issue. The most common causes for dirty circuit boards are water and broken cases. A damaged case could let water and other debris to enter the circuit board, which can cause it to short. Water can also get through pins and vias, which are tiny connectors that are found on the board.
If you are handy enough to open your key fob and you don't mind making an mess, you can take the buttons out of their sockets and put in new ones. Also, you should check the connections between battery terminals. They can become extremely filthy and if they're not tight enough, the buttons might not work or may even remain in their down position. Soldering terminals and buttons back into place is usually enough to bring a non-working fob to working.
Non-Remote transponder chips
The non-remote chips sealed in a sealed case are more durable than their remote fobs, but they are susceptible to cracking in the event of a hole being drilled in them, or in the event that a door handle of a car or lawnmowers is pushed over them. Fuse failures are usually to blame for non-remote chips failures.
If you're handy enough to remove the sealed key fob and are able to bear the mess, you can easily remove the circuit board and examine the fuse with an instrument to verify diode function. If you're not comfortable with this, you can go to your local Oreilly or hardware store and use their RF frequency tester. This will tell you whether the key fob transmits a signal.
Programming
Key fobs are not indestructible and can be damaged through a variety of causes. They can break their connection with the receiver in your vehicle due to shocks or a low-battery, which requires changing the program. A professional auto locksmith or dealer can reprogram your key fob to get it back up and running. In the event that resetting and fixing your key fob doesn't work it may be time to replace it all over again.