I believe it is mounted below the battery tray in the engine compartment
Mercury Mountaineer was created in 1997.
Under the battery tray. A little difficult to get to bu tnot too bad.
replace it.
The mountaineer has a fuse box under the drivers side dash ,and it has two horn fuses , right horn fuse ,and left horn fuse.
According to the ( 1999 ) Mercury Mountaineer Owner Guide : ( the length is 188.5 inches )
There are two head gaskets in the V 8 1999 mercury mountaineer
In a 1997 Mercury Mountaineer : In the Power Distribution Box ( which is " live " ) located in the drivers side of the engine compartment ( relay # 2 is the horn relay )
I BELIEVE the horn is mounted below the battery tray
According to the 2006 Mercury Mountaineer owners manual : ( # 14 is a 20 amp fuse for the horn ) * in the fuse panel below the instrument panel on the drivers side *
looking for a diagram for 1999 Mercury Mountaineer. Need to take the fuse out for the seatbelt alarm, it will not shut off.
The 1999 Mercury Mountaineer owners manual shows : unleaded fuel only - 87 octane as the recommended fuel
The sub woofer size on a 1999 Mercury Mountaineer is 5 inches by 7 inches. Speakers are located in the front and the rear of the vehicle.