Might be able to get at in from underneath but probably will have to remove the dash cover
It does have both tail lights as well as dash lights
on the dash
under dash on drivers side
The 1996 Mercury Sable the OBD 2 connector is under drivers dash next to kick panel
its a gray bubble on the dash close to the glass
Just to the right of your headlight switch in the dash is your gauge panel dimmer control . Rotate the wheel up to brighten your dash lights . ( also , if turned all the way up it turns on your interior lights )
The horn relay for a 1998 Sable is on the back of the distribution block. The block is under the dash on the drivers side.
Either your parking brake / emergency brake is on or the BRAKE FLUID LEVEL is LOW , in the brake master cylinder located in your engine compartment
You have to learn all the new controls(??)Seriously though - See "Related Questions" below for more information about dash converter kits for this generation of Taurus / Sable and how to install an after-market unit.
Start with the headlamp switch.
Good news: No - so much easier than that! See "Related Questions" below for lots of help in making the replacement...