I got tired of having the map display on my NAVI unit go to the dark mode when the headlights were turned on during the day. I grabbed a few feet of wire, some connectors and a switch and fixed the problem.
The display on my unit is wired to the dash lights for the HVAC control unit. I cut the red wire and spliced two yellow leads into it. The two yellow leads go under the dash to the switch and provides a cut off for the headlight signal so when I am using the NAVI in the daytime with the headlights the map display is still bright.
Took me about 15 minutes and it works great. No more trying to read the darkened map during the day!