I was looking at a picture in the 2003 Mercury Grand Marquis Owner Guide and it shows the power steering fluid reservoir at the front of the engine compartment between the engine coolant reservoir and the engine air filter box
It is on the back of the power steering pump. The power steering pump is located on the left hand side of the engine. It will be a cap with the dipstick molded on to it. Remove the cap and you will be able to see the fluid.
On a 2000 Mercury Grand Marquis : The fuse box is below and to the left of the steering wheel , by the brake pedal ( it has a cover on it ) Also , the Power Distribution Box ( which is " live " ) is located in the engine compartment
In a 2000 Mercury Grand Marquis fuse ( # 16 ) is a 20 amp fuse for the cigarette lighter ( in the fuse panel below and to the left of the steering wheel by the brake pedal , the panel has a cover on it )
On a 1996 Mercury Grand Marquis : The fuse panel is under the dash , to the left of the steering wheel column ( it has a cover on it ) Also , the Power Distribution Box ( which is " live " ) is located in the engine compartment by the battery
My leaks power steering fluid -- MOST of the time is it the hoses. Try replacing those first. You'll need a good mechanic with the proper tools to replace the pump. But I'd bet one of the hoses is rotted.