LCD Marine Meters

I Have twin LCD meters and A multifunction display. When illuminated at night the display has no contrast and is virtually impossible to read. All three have the same problem. Has anyone experienced this and what causes them all to be unreadable. In the daytime they are fine. Could it be the backlighting? Help please....

[boats.net]

Check to see if it is maintaining 12 volts on yellow wire at gauges with everything turned on to see if it's a low voltage problem.