Oh dear, what have I done

[allover]

My sons Spanish 2008 Navara D40 started to play up again, obvious culprit being the scv valve, replaced successfully with a Denso short scv and working great again.
But i now have no power steering. My question is what could i have done to affect the unit as there appears to be no loose pipes, i don't even know where the power unit is! Any advice taken

 

[YD25Frontier]

It's either you lost the belt, low on fluid or pump failed. That's where I would start. It's mostly a mechanical/hydraulic system. I don't even think they have an idle up sensor on the diesel models like the gas versions.