focus central locking?

Hi
Had same problem as everyone it seems on my daughters 1999 focus .Located the number 63 fuse behind the fusebox .Fuse had blown so replaced it, straight away i heard the locking mechanisms make a noise but as soon as i locked the door the fuse blew .I tried this twice same problem,any sugestions on where to start to find the problem of diagnosing what is causing the fuse to blow.
thanks jim