Just fixed this on an 01 Ranger.

Take the plastic cover around the steering column off. On the side of the ignition lock cylinder, you'll find a wire attached to a metal contact and a bit of plastic. This is for the key in chime. The plastic breaks and it lets the contact touch the metal side of the lock cylinder.

You can fix it by gluing it back in place and it will chime only when the key is in and the door is open, or you can just tape up the contact and it won't chime at any time.