One problem related to horn assembly has been reported for the 2000 Mercury Grand Marquis. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2000 Mercury Grand Marquis based on all problems reported for the 2000 Grand Marquis.
Under wet conditions horn will activate by itself. Without applying pressure on horn, horn will sound for about 1-30 seconds. When it stops, inside and outside light will turn off for about 2 seconds. Vehicle was at the dealer 4 times, but could not determine cause.