2001 Limited, Locks won't lock,more...

[bsutton]

I own a 2001 Limited and recently the locks started to malfunction. They will not lock with the interior buttons, the key in the door or the remote. All the doors are closed tightly but still nothing happens. If you manually lock the doors they will unlock as normal using all three methods. Is there a lock and unlock module that may of failed? Any help would be appreciated.
Thank you