The cost for a power steering pump for a 2005 Buick lesabre custom with a 3.8 liter engine

SOURCE: Power Steering pump appears to be leaking but is full????

Just guessing. Could it be a warped brake disk? That would cause vibration. And vibration in steering might conceivably cause splashing out the power steering reservoir. You would know if the disk were warped by a shudder when you brake at hight speeds.

SOURCE: 1999 Buick LeSabre Power Steering

next to firewall below the alternator

SOURCE: Location of power steering reservoir

This pump sits down below tha alternator. If it does not have a remote resevoir than the resevoir sits on top of the pump. It is a pain to get to.

SOURCE: How do I reset my Check Engine Light?

you could go to an auto parts store and they can reset it for you, or you could pull your battery cables off the battery and hold them together for about 10 sec. that will clear any codes.

SOURCE: Where do I add power steering fluid?

The power steering pump is in the front of the engine. You will see the serpentine belt on the pulley and it will look something like htis picture. The pump has a resevoir with a cap on top which is removable and has a dipstick built in to tell you how low you are on fluid.