I need the fuse box schematic for a 1992 ford crown victoria.

In some large cars like yours you can remove the rear seat back and open a plate that gives access to the trunk. Depending on your car if it is just a small access panel you will have to go on a fishing expedition with a magnet attached to a rod of some sort to fish them out.

See if this site has one:
http://www.bbbind.com/free_tsb.html don-ohio

can be seen here:
2001 Ford Crown Victoria Owner Manual Page 158 http://www.manualowl.com/manualswf.php?id=1289&manual_type=auto&d=bced2dacb3b142024bde8584f72ef81d

If you are keeping this vehicle and do your own work on it, I 'd recomend going to ebay and buying a original Ford EVTM (electrical vacuum troubleshooting manual) for your specific vehicle. It is a very simple and well illustrated book to understand.
I have one for my 1992 crown vic. It show a 40 amp fuse in the engine compartment fuse box for the lights.

Fuse junction box is located to the left of the steering column. remove the instrument panel steering column cover

instrument panel fuse panel: Below LH side of instrument panel, left of steering column

http://www.supermotors.net/registry/media/448623

it should under the lid of the fuse box and in the owners manual if no manual try here for one online www.edmonds.com

ITS FUSE #16 AND ITS a 20A FUSE

it should be in your owner manual. if not, I can look up something for you but can't post illustrations to this site.