How to Fix a Key Fob That isn't Working
If your key fob does not work and you're not sure why, you can fix it with some simple steps. First, make sure that it's not the 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 isn't working. The majority of car remote key malfunctions are caused by circuitry or battery issues.
Battery
It is not uncommon for the battery in a key fob for cars to get worn out. It is fairly easy to change out a battery, although it is important to ensure that you choose the correct type and you can consult the owner's manual or talk to the dealer of the manufacturer to determine the type of battery you need. It is also essential to inspect the battery compartment as dead batteries can leak caustic chemicals which can damage the remote. If replacing the batteries doesn't solve the problem, it may be that there are other issues that require attention from a professional. If buttons are damaged or stuck, for example it could be necessary to remove the remote and rebuild each component. You could also try reprogramming your vehicle to recognize the new key fob.
Buttons
Due to frequent use, key fobs may get dirty and worn. It is not uncommon to have buttons stop working, or to require a long press to get them working. This can be extremely frustrating especially if you're out of town and need to start your car. Fortunately, even worn-out or malfunctioning buttons can often be fixed with a little time and a few items you have in the house.
First, check that the batteries are charged correctly and that the indentation on the back of the button is filled. Then, carefully open the remote and inspect the circuit board. Check for signs of corrosion or other signs that the buttons are worn out or damaged, like missing conductive paint. Then, using the Q-tip, dipped in alcohol to gently clean any membrane contacts that have become damaged or have conductive paint missing. Be careful not to rub too hard, as this can erode the conductive paint and block the button firing when pressed.
Also, carefully check the battery connector's terminals to ensure a loose solder connection. Soldering them back in place can restore the button's functionality if this is the situation. 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 stop working or require a long press to function it is likely the graphite disks that are on the back of the button are wearing out and need to be replaced. This can be done by rubbing a pencil on the disks, which should bring the button back to its original state.
If none of this is useful or if the button doesn't respond to a hard press, then it may be because the circuit board is damaged. This can sometimes be repaired by a quick clean, and re-soldering, but it is ideal to have a spare fob available in the event this method doesn't work for you.
Circuitry
The circuit board in your 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 frequent causes of boards that are dirty. A broken case can let water and other debris to enter the circuit board, which can cause it to short out. Water can also damage pins and connectors that are small on the board called via's.
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 solder in new ones. It's also worth looking at the battery terminal connections. They can become very filthy and if they're not tight enough, the buttons might not work or even stick in their down position. Soldering the terminals and buttons back in their place is generally 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 they are contained in, but they can still be cracked by a hole that is drilled into them or over by a lawnmower or door handle for a car. Failures of the fuse are typically to blame for non-remote chip failures.
If mobile car key repair 're not comfortable opening the key fob, you may remove the circuitboard and use a multimeter to verify that the diode is operating properly. If you're not comfortable doing this, go to your local hardware store or Oreilly's and they will usually have a RFID frequency tester that can let you know whether the key fob transmitting a signal.
Programming
Key fobs aren't indestructible and can be damaged through a variety of causes. broken key repair can lose their pairing to the car's receiver due to shock or a low battery, which requires the reprogramming. A professional auto locksmith or main dealer will be able to reprogram your key fob to get it working again. If resetting or fixing your key fob fails, you may need to replace it.