l have a 1997 Mercury Grand Marquis and the headlight switch broke. l went to get a new one, and the price was $179.

l found out through other sources that the 1999 Grand Marquis used basicly the same switch, the differences being the backlighting on the 1999 switch is a different color, and it does not have an Auto lamp indicator LED (big deal).

The price for the 1999 switch is $79.

Can someone please explain to me why there is a $100 price difference?

Certainly. The other switch is not the right one and does not have the right specifications, even though it might work. And the bottom line is this, that is a part that there is not a heavy call for, and essentially only available through the dealer, who can charge whatever they want for it.

l do not know about the prices for a new switch, but you might consider going to a wrecking yard to see if you can get a compatible switch off a wrecked car. l suspect you wo not pay nearly as much as either of the prices you mentioned above, especially if you are able to retrieve the part yourself!

The auto lamp feature is the big difference.

Auto-lamp turns your lights on automatically and its wired to a photo sensor. Basically, its a completely different set of wiring and system.

check out car-parts.com and u will get a listing of all the junkyards that have your car. give them a call and have them mail it to u.

It is called a rip off.