If you turn on the lights and the screen doesn't dim and the nav doesn't go into night mode then your ILLUMINATION wire is not connected correctly or at all. You can flash your lights till the cows come home and it won't do a darn thing. When it gets dark out does the nav go to night mode? If so then your ILLUMINATION wire is tapped off the light sensor not the headlight switch.
If it's night time or day time and your Z1 never dims and the never goes into night mode then you need to hook up the ILLUMINATION wire.
If the unit does dim but only when it's dark out. Then you will need something else to "flash your lights". You could work up a diode and toggle switch, but it's probably easier to buy my flasher circuit.
Or if turning the lights on doesn't change it to night mode unless it's dark out, you could hunt down a wire somewhere else in the truck which goes to 12v when the lights are on no matter what the light level outside is and then you can manually flash your lights or use your auto starter.
I sell my circuit at
www.sminntech.com if you didn't know where to get it.
Also the timing of the light flashing is very important. It's not just flash them some time after you boot up, there is a 2 second window you have to hit and it changes a bit depending on how the unit is booting up.