I actually found out this by accident. The only thing my Keyfob for my wife's Monterey would do is unlock the Doors. It Wouldn't lock them or open any of the doors. I tried new batteries, cleaning the internal parts, I even opened my wife's Keyfob to see if it had dielectric grease on the contacts. I had to disconnect the battery to do some work on the Vehicle, now both Keyfobs work perfectly.