2000 Ford Expedition Steering Problem

I have a 2000 Ford Expedition and have recently run into a steering problem. When I go to make a hard turn whether it be making a complete U-Turn or 90 degree turn, the truck does not want to move? The power steering fluid is normal and there are not any leaks. Could this be a belt issue (which also all the belts seem to check out) or the steering pump itself?

Train left front tire meaning?

My Ford Expedition left front tire got this message as started it tonite. It said "Train Left Front tire" What does this mean?

Which one would you buy and why?

2018 Chevy Suburban
2018 GMC Yukon XL
2018 Cadillac Escalade
2018 Ford Expedition
2018 Lincoln Navigator
2018 Nissan Armada

The reason I'm asking is that I'm planning to purchase one of these soon.