One problem related to headlight switch has been reported for the 1999 Mercury Grand Marquis. The most recently reported issues are listed below.
Problem: intermittent headlight failure while driving at night with 1999 (1998 year of manufacture) Mercury Grand Marquis. Lights go off for as long as 2-3 seconds and come back on again for a second or two, then go off again, then back on again, etc--and only occurs after the vehicle has been driven for 20-30 minutes. This happened once before, about two years ago, with this very same vehicle and I solved the problem by replacing the headlight switch on the dash. Apparently there is no headlight-related recall* for this particular Mercury and the cost to dig deeper into the cause of this problem by the Mercury dealership will be therefore at my expense. The cheapest repair cost scenario at the dealership is over $300. This problem should not have occurred under any circumstances in the first instance, not to mention now the second time. : nhtsc recall # 99v103 Mercury mystique (1998 year of manufacture).