What makes the headlights on a mercury grand marques not come on at night.

(LCM)lighting control module is bad and very expensive.MAY BE A RECALL ON THIS.it's located just under the steering column.$300.00,reman.-$550.00,new at parts house.check for recall.you are not the only one with this problem,several hundred more also!you can have the system scanned,it will store a code if that's the problem.

The LCM (lighting control module) is a known fault. I replaced mine in 2013 at a local shop, and in 2014, I received a notice from Ford telling me they would cover one replacement in the lifetime of the car. I took my receipt from the local shop to the Ford dealership and the dealer refunded the money I paid to the local shop for the repair. If you haven't done the repair yet, ask the dealer about the warranty for the part.