I have the same problem ... the prior owner (which happens to be the MANAGER of the Toyota dealer where I bought my Explorer) claims he moved and has not yet found the Owner's Manual with the Owner's Card containing the Factory-Set Keyless Entry Code for the Door Keypad.
I called Ford's 800# and was told that since I am the 2nd owner, they no longer have the Code and that my only option was to go to the Dealer.
Supposedly, they now have a DIAGNOSTIC WAND that is used to determine the Factory-Set Entry Code.
Good luck
