to replace the remote entry you should purchase it at the dealer or local parts store. the dealer is better because they can order the same remote, and have the acess to re programme the remote to factory settings ,
The replacement on the Toyota remote entry could be possibly hard or easy. It depends if you are just trying to replce the actuall remote or the system inside of the car. If you are trying to replace the remote you may only need to contact your dealer and they may be able to supply your with the product.
