Remove the front door sail panel. There you will see 3 bolts holding the side view mirror. Remove bolts, replace / or fix side view mirror. remove the wire hardness. Installation is the reverse of removal.
a junkyard
Depending on and if the mirror holding clip came off the windshield. If it came off windshield you will need to buy a rear view mirror installation kit. Follow instruction on kit to be install.
how to install driver mirror
Your local Ford dealer will have the wiring diagram for the mirror control switch for the Expedition. They have all the manuals with the diagrams.
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Many automotive glass shops will sell just the mirror glass or alternatively they will install it for you.
look in junkyards or go to the Pontiac dealer. best places to find stuff like that
pop of the plastic cover on the inside of the door it is only cliped on, undo the 3 bolts unclip
If yourr talking about the side view mirror switch then it pulls right out.
on my 1988 i had to first remove the door panel and then reach up there and hold the little bracket and then unscrew the mirror and dont forget to unplug it is electric and reverse it to re install it
Check out the guide to replace the side mirror on a 2001 Ford Expedition http://www.techwarelabs.com/articles/other/Ford_Expedition_Side_Mirror_Replacement/index.shtml
Go to this website. It will show how to remove the door panel and the side mirror.