Is the power steering causing my Yukon to not make tight turns like it usually does?

Have you checked the power steering belt and the fluid level in the power steering reservoir? The belt may be slipping or the hard turn may have caused a leak in one of the hoses that power the unit.

a steering wheel shake with the wheel fully turned usually indicates a seizing constant velocity joint (axle). it can also be accompanied by a clicking noise while turning at higher speed. this is easy to confirm. raise and support the front of the vehicle and put in neutral. turn the wheels by hand with steering wheel pointed straight ahead. there should be minimal resistance. then try rotating the wheels with the steering wheel turned all the way to one side then the other. if you feel any extra tightness or binding, you indeed have a seizing joint. if the axles look ok visibly, you will need to remove the axles to confirm which side is the problem. good luck!

Turn car off - Remove power steering cap, and turn streering wheel hard right or left and fluid should pour out (cover surroundings with rags.) If so, check your power steering pump.

sounds like a bad wheel bearing.

well your power steering pump could have went out, but crank it up take the lid off and look inside while someone turns the wheel and see if the fluid is moving around and then have them do it while its in park wile giving it some gas and check again to see if its moving if not its probably went bad

The Chevy Equinox has an 80 Amp mega fuse that tends to fail and cause all sort of power steering and Stabilitrak issues. Before I messed with the belts or power steering pumps, I would check the fuse first.

Find the leak and repair it...It is a sealed system, if you are adding large amounts of power steering fluid, it is leaking out somewhere. Hoses, reservoir, steering box, power steering pump are places to check. You should only have to add minimal fluid to the system for the entire year.

The immediate squeal you hear is most probably the unit is out of fluid or has leaked onto the serpentine belt and causing it to slip.
Fix the leak and check your serpentine belt for wear.

blow that dang truck up

Sounds like you may have a problem with the power steering pump. Notorious for these pumps shaft to break, causing "armstrong" power steering. As far as the 4wd low problem, ick.

Check to see if the power steering pump is still turning. If you have a broken drive belt (serpentine belt or "fan" belt), and the pump doesn't turn, you have no power assist. If the pump is still turning, check the fluid level in the reservoir.