Three problems related to wiring have been reported for the 1998 Mercury Grand Marquis. The most recently reported issues are listed below.
Low/high beam lights inoperative in park or drive, bulbs & wiring checks good, 25 amp fuse was blown, but replaced fuse caused no change.
Electrical short on 1998 Mercury Grand Marquis causes engine to stall at highway speeds. Power brakes and steering not operable when engine stalls. Cannot restart engine when condition occurs. Car towed all three times. Problem documented in Ford service bullitin 12950. Problem occured 3 times: November 2003 October 2004 November 2004.
High beam headlamps malfunctioning, due to loose wire.