When my truck warms up and I drive it long enough it makes a whining noise sounds like a power steering whine, and it only does it as the Rpms go up. I put it in neutral and reved it and it still did it going down the road, but when I got home I reved it and couldn't hear it but as I reved I pushed my brakes all the way I could hear a whine. the whine isn't a terrible whine just enough to get on your nerves. Any help is appreciated, thanks.

 

Low fluid in the P.S. pump! Works the brakes too! Or the pump is going bad!

 

Yes check your powersteeing fluid and may have a pump going bad. These trucks have hydro boost brakes that run off the powersteering system if you loose pressure in the system you will loose your brake assist.