About a month or two ago my driver's side lock (the ****) would budge a little when I hit the "door lock" lever on either front door, or when I turned the key to lock all doors in the passenger door. Sometimes the driver's side lock would lock, other times it wouldn't.

A week or two ago the same thing started happening in the passenger side door. So at this point, if I unlock all doors, usually only the back doors actually unlock. The front doors have to be unlocked by key at that door.

Also, when I lock all doors, normally the opposite door doesn't actually lock so I have to walk around to lock it. I have to visually look at all door locks before I leave it now, since on occasion some have not been locked when I though all doors were locked.

Any ideas? I was thinking that maybe the battery is losing juice (the car is almost 5 years old, with ~ 55,000 miles on it).

 

If the battery was dying, the car would show more symptoms than just locks. The locks don't take that much juice to operate.

It wouldn't hurt to check the wiring to make sure it's getting enough power to the switch and lock solenoid. The solenoid itself could be bad. Also check the locking mechanism for any worn, bent or broken parts.