vnehess, isn't there a printed manual in your glove box?
On p. 290/461 (not sure if this is the unit in question) the illustration shows a button just right of top center labeled:I don't believe there is any control that will dim the display.
:laugh:. . .
In fact the manual is in the truck, perhaps that will serve to dim the display, by placing it directly in front of the screen :^)