I am stumped at the moment.  I posted a few days ago about a FMX Field IQ issue I was having.  I have progressed but with a lot of stress!  I am presently trying to do a drive calibration and it  will show some real low rpms and part way through the calibration it will say that no hydraulic fluid or it gives a whole list of potential problems.  I know that I am getting hydraulics to the drive units but I suspect that the solenoid valve is not opening up.  By the way this is on a MX 255, the planter is a 1720 with 3 Pwm valves and motors to do sectional control and rate.  No clutches.  I have updated the Field IQ software to 3.02.  The FMX is running version 6.6.  I have tried the hydraulic hoses in different remotes, with different position as far as pressure, still no dice.  I had to disable the implement switch too because I cannot calibrate that in the display.  Any thing I am missing?  Sorry for taking up so much of your time and I appreciate any input.  I guess this is what happens when a 64 year old guy gets too far down the road with some of this advanced tech stuff!!