I open the door to look out on to the ground lines while I back up into my parking space, some times I get this double beep without any warning lights on the dash. Any idea what the beep is for?

Took a video with the double beep at the end.

 

My back up camera has lines on the screen? I use those as I can see the painted lines on the ground too.
Funny thing I just found out is some of the new pickups will not move if the drivers door is open. Safety feature.
.
.
.

 

Not absolutely sure, but you might set your suspension accidently to the "tight tolerance mode" what are used for adjusting headlights. It went something like this: Open drivers door, press brake pedal 3 times inside of 2sek window, close drivers door - you get 2(?) chimes for confirm. Suspension go to normal mode in next start.
Like i wrote, i am not complete sure for this. Haved done it once, about 4 years ago, after i changed the bulbs.

 

My parking space requires me to be exactly on the line to leave some space for the car next to me to open its doors. Welcome to Hong Kong, where every inch of space counts!

 

Any more info about the "tight tolerance mode"? I have adjusted my headlights but just parked the car on flat ground when I made the adjustments.
Does it lower the car?
.
.
.

 

Hi. No it do not lower the vehicle, but set the rear suspension closer its initial height. In normal mode the height have wider tolerance berore suspension make corrective action for it.
Example, in normal mode you can sit in or step out and rear suspension will not correct the changed height. (well, depends how much you have collected "spares" on your weist or just happened to have big bones) Note: Only rear have air suspension in x351 model.