Can electrical locks on a 2002 Mercury Sable be replaced with standard locks?

The key works fine in the ignition system. Likewise in the trunk lock. It's only in the two door locks that it doesn't really work. I was told that there is a transponder in the key. Does that mean that I would have to have this kind of key whether or not I left the fob behind, that only this kind of key will work with the system? Thanks in advance for any advice.

Since the key still works fine in the ignition and trunk, a locksmith or you can remove the problem cylinders from the car and the locksmith can RE-Key the cylinders by replacing the worn internal pins or wafers making it work fine on the original key, or simply can replace the worn cylinders with brand new ones and key those to the original key. As tennisshoes said, the locking systems are the same , the only difference is an electric motor or solenoid with a rod that connects to the locking system to lock and unlock, so they have no affect on your problem at all.This way you will still have the same transponder key & if you have an alarm or disabling system operated by a key fob, you can just keep the key fob attached to the key and use it only for operating the alarm system.

Ah. Okay. As always, I appreciate all the help with this question and all the options you've given me. However, I'd still like to know whether it would be possible to year-zero this thing by changing the locks and ignition to just regular, old, non-transponder-type keys and locks. Thanks.

Chances are not too good I would suspect. As I said, the door locks do not have anything to do with the transponder chip in the keys. The transponder chip only sends a signal to the ignition system via the car's on board computer. My best guess is this: If you can find an earlier style ignition lock cylinder that will fit into your current car and still turn that is the easiest part. The next thing you would most likely need to do is have someone access the computer and reprogram it to eliminate the need for the transponder key or at the very least try to rack the wiring for that part of the disabling system and disconnect it then see if the car will still start and run normally with no ill effects.

Thanks yet again. Pretty much every question I had about this issue has been answered.