it's just telling you what mode the drive system is in when it goes through it's startup check.
There are 4 drive modes available to the operator
D1 through D4, D1 being the slowest mode and D4 being the fastest mode.
If the truck has premium hydraulics(scr controlled) it should also display a P1 throught P4 which translates to the same mode speeds respectivlely.
the buttons on the display should allow you to change these modes if pressed in the correct sequence.
This is ONLY to be used to report flooding, spam, advertising and problematic (harassing, abusive or crude) posts.