How to Fix a Key Fob That isn't Working
If your key fob does not work, you can fix it with a few simple steps. First, make sure that it's not your backup remote.
If your backup remote is unable to unlock and lock the doors of your car, then it is likely that the main remote is not working. The most common causes for key problems with your car remote are circuitry or battery issues.
Battery
The battery in the key fob could be worn out over time. It is easy to replace batteries. However it is crucial that you use the correct type. You can refer to the owner's manual or contact the manufacturer to find out the correct type. It is also essential to check the battery compartment, as dead batteries can leak caustic chemicals which can damage the remote. If changing the battery doesn't fix the problem there could be other issues that require professional attention. For example, if buttons seem stuck or damaged it could be necessary to take the remote apart and rework its components. It is also possible to reprogramme the vehicle to recognize the new remote.
Buttons
From frequent use, key fobs can get dirty and worn. It is not uncommon to have buttons stop functioning, or require a hard press to make them work. This can be very frustrating especially if you're away from home and need to start your vehicle. Fortunately, even worn-out or malfunctioning buttons can often be fixed with just a bit of time and some of the materials you might already have in the house.
First, make sure that the batteries are correctly inserted and that the indentation on the back of the button is filled. Open the remote carefully and inspect the circuit board. Look for evidence of rust, or other signs the buttons are worn or damaged. For instance the paint that conducts electricity could be missing. Then, using a Q-tip dipped in alcohol, gently clean any membrane contacts that have damaged or where conductive paint is missing. Avoid rubbing too hard because this could damage the conductive paint and block the button from firing when it is the button is pressed.
Also, be sure to check the battery connector terminals for an unattached solder connection. Soldering them back in place will allow the button to function again if this is the case. The same method can be used to restore functionality to any other loose connections in the fob.
If, for instance, any of the buttons made of rubber that are on the front of the key fob have stopped working or require a long press to function it is likely that the graphite disks that are on the back of the button are wearing out and require replacement. You can usually do this by rubbing a pencil over the disks. This should bring the button to life.
If all of this doesn't help, or if the button does not respond to a firm press It could be the case that the circuit board has gone bad. It is possible to fix the issue by cleaning and re-soldering your fob but you should also have another spare in case it does not work.
Circuitry
Whether or not the keys fob buttons are functioning, the circuit board inside the remote could be dirty. A thorough inspection will usually resolve this issue. The most common causes of dirty circuit boards are water and broken cases. A damaged case can allow water and other debris to pass through and short circuit the electronic components. Water can also get through pins and vias, which are tiny connectors that are found on the board.
If More Material enough to open your key fob and you don't mind making an mess, you can take the buttons out of their sockets and solder in new ones. It's also worth checking the connections between the battery terminals. They can become extremely dirty and if they're loose the buttons may not work or even stay in their down position. Soldering the terminals and buttons to their proper positions is usually enough to return a malfunctioning fob to a working condition.
Non-Remote transponder chips
Sealed non-remote transponder chips are much more durable than remote fobs they are contained in, however they are still susceptible to being broken by a hole being made in them or pushed over by a lawnmowers blade or door handle for a car. The failure of the fuse is usually the cause of non-remote chip failures.
If you're not comfortable opening the key fob, you may take the circuit board off and use a multimeter to check that the diode is working properly. If you're not comfortable doing this, go to your local hardware store or the Oreilly's and they'll usually have a RF frequency tester that will determine whether the key fob is sending a signal.
Programming
Key fobs aren't indestructible and are susceptible to damage by a variety of factors. They may lose their connection with the receiver inside 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 and get it up and running again. If resetting or repairing your keyfob does not work it is possible to replace it.