Take a look at this.
Or google for dummy VGA.
I would like to try hooking my laptop directly to my factory nav screen. However, after hooking up the RGB and sync pins, the vga port does not detect that a display is connected (extend desktop button in windows wont work), so I cannot get anything to display.
I have verified the VGA port is good by trying it with a real monitor. Its only when I try to wire it up in the car, that I'm having issues. So its probably something I forgot to wire in.
Anyone have experience with this? Is there a pin on the VGA connector that I need to ground so that it detects a display is attached? How does the VGA port know that a screen is attached?
BTW, I realize the resolution will most probably be poor in comparison to a true VGA screen, but nonetheless I'd still like to try this out.