I use a transfer pump and just empty the reservoir, re-fill it with fresh fluid, steer it back and forth a few times and repeat until it comes back out clear.did you do the flush where you suck the res dry, take the return line off it, plug the reservoir. then fill it with fresh fluid, jack the wheels up and turn the wheel right and left with the engine off till clear fluid comes out?
I've not done this yukon cause it doesn't have a pump but I did the c6 cause that thing murders powerstering fluid even with the optional cooler. it took like a qt and a half, the Tahoe system must be huge to run a gal thru
I don't like to mess with the lines if they are not leaking I just leave it hermitcally sealed less possibly for issue's later in my book, but some people take one line off and run it out that way.
the 2015+ are all electric steering so ours is the last gen to have a actual pump