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 by following a few simple steps. First, check to make 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 frequent causes of car remote key failure are battery or circuitry issues.
Battery
It is not uncommon for the battery in a car key fob to get worn out. It is quite simple to change out the battery, however it is important to ensure you select the correct one and you can consult your owner's manual or contact the manufacturer's dealer to find out the kind of battery you require. It is recommended to inspect the battery compartment thoroughly because dead batteries can release caustic chemicals that could damage the remote. If changing the batteries doesn't solve the issue it could be that there are other issues that require attention from a professional. If the buttons are broken or stuck for instance, it may be necessary disassemble the remote and rework each component. You could also try reprogramming the vehicle to recognize the new device.
Buttons
From repeated use, key fobs could become worn and dirty. This is not uncommon however, it can cause buttons to stop working or require a very hard press for them to work. This can be very frustrating especially if you're away from home and need to start your vehicle. Fortunately, even worn-out or broken buttons can usually be fixed with a bit of time and some of the materials you have in the house.
First, make sure that the batteries are correctly installed and that the indentation at the back of the button is filled. Open the remote carefully and inspect the circuit board. Look for signs of corrosion or other signs that buttons are worn out or damaged, such as missing paint that is conductive. Use a Q-tip that has been dipped in alcohol to gently clean any membrane contact that has become worn out or where conductive painting is missing. Avoid rubbing too hard, since this could cause damage to the conductive painting and prevent the button from firing when the button is pressed.
Also, be sure to check the battery connector's terminals for an unattached solder connection. Soldering them back to their original position will restore the button's functionality if this is the situation. You can use the same procedure to restore functionality to any other loose connection within the fob.
If key fob repairs of the rubber buttons located at the front of the keyfob isn't working or need to be pressing very hard, the graphite disks at the back of the button could have worn out and will require replacement. You can do this by rubbing a pen over the disks. This should bring the button back to life.
If none of these solutions work or you are unable to get the button to respond when you press it hard, it could be that the circuitry has failed. This can be fixed with a quick clean and refitting, but it's best to have an extra fob on hand in the event that this method doesn't work for you.
Circuitry
Whether or not the key fob buttons function the circuit board that is inside your remote might be dirty. A thorough examination is usually enough to fix this problem. The most common causes for dirty circuit boards are water and damaged cases. A broken case can allow water and other debris to enter the circuit board, causing it to short out. Water can also damage pins and connectors that are small on the board, referred to as via's.
If you're able to open your key fob, and you don't mind making an mess, you can remove the buttons from their sockets and then solder new ones. Also, you should check the connections between the battery terminals. If they are loose, the buttons may not function or get stuck in their down position. Soldering the terminals and buttons into place is usually enough to return a malfunctioning fob back to working.
Non-Remote transponder chips
The sealed non-remote chips are more durable than remote fobs, however they are susceptible to cracking in the event of a hole being drilled in them, or if a car door handle or lawnmowers plows over them. Most of the time non-remote transponder chips fail, and this could be attributed to an exploded fuse.
If you're handy enough to open the sealed key fob and are able to bear the mess, you can remove the circuit board and examine the fuse using a multimeter for proper diode function. If you're not comfortable with this, go to your local Oreilly or hardware store and utilize their RF frequency tester. This will inform you whether the key fob sends a signal.
Programming
Key fobs endure many abuses and aren't impervious to damage. They may lose their connection with the receiver inside your vehicle due to shocks or low battery, which calls for the reprogramming. A professional auto locksmith, or a dealer in the main can reprogram the keyfob and get it functioning again. If resetting or fixing your key fob fails, you may need to replace it.