Instruction: Generate an answer to the question by utilizing the information contained in the document.

Input:
Question: Where does the blue wire connect and what does it do?
Document: I added enough length using black 110 volt lamp cord (Hardware Store bought). The blue wire attached to the camera circuit wasn't needed by me but, for those who want to know, it's a wire that acts as an "on switch" which you connect to any positive lead on any circuit that turns on when you, say, go in reverse. It will turn on the rear view camera circuit. But I cut it off so it wouldn't get in the way of anything.
My truck camper makes it difficult to see what is behind me. I hang the monitor on the rearview mirror. Installation instructions are sparse at best, but I wired it up before actually installing it to ensure I knew what wires went where. The blue wire is the backup wire. Connect it to the backup light for backing monitor only. I connected it to the license plate light to function as rearview and to remind me to turn my lights on when I travel.
One tip for other installers: the blue (acc) lead from the display is like the trigger lead for power amplifiers: you must wire it so that it receives power when you want the screen to come on. If you are using it for a back-up cam, then run a wire from the reverse light circuit to both the camera and the display.
I wired up the monitor, and attempted to turn it on. Behold! It flashed blue once and no display appeared. I made several attempts to turn it on, but nothing. Checked all my connections...they were fine.Amazon will not send a replacement for some reason. I have to return it and get a refund.All in all, this was not a good expereince. I hope no one else gets the type of junk I did.
This turned on the camera and the monitor only when I was in reverse. I replaced the flimsy tiny 20 foot video cable with coax cable (this is the cable used in your house to connect the tv to the cable company outlet. There are 2 sizes so you will need to buy the appropriate male RCA connectors, 1 for each end. You can buy the connectors at Home Depot and the tool to compress the conectors to the cable there as well.
I had to extend the cables after searching around on the internet the extension cable for this monitor and of course they were nowhere to be found. So, I had to use wires from my old wireless back up assist and manually connect them to those of the monitor. On the other hand, the RCA male cable for image (yellow one) which connects the camera to the monitor is way too long that you have to fold it because the distance from the taillight to license plate camera is really way too short.
The only information is that it is &#34;Aux&#34;. It would help if the function of this wire was included.RCA male connectors have very thin exterior contacts. Not sure how they will holdup.
The monitor was great, the wiring is a little short for my SUV. the bracket for the camera is a little too flimzy. A suggestion; send along more wire for the rear camera to attach to the back-up light wiring and also more wire for the front monitor.
Note that I've already connected the camera to the monitor via its video RCA type connections.Oh, and by the way, those claiming the video wire length or quality isn't good...are wrong. Works perfectly first time and all the times after.Works like a charm...with one caveat.The camera isn't wide angle enough.
Second. I originally wired the monitor to the cigarette lighter so that it would turn on only while the key was on. Bad idea. The first drive with it was just after the sun went down and the monitor was so bright in my face that I could not see to drive. My solution to the issues was to wire the power to both the camera and to the monitor from the back-up light in the back of my quad cab full size pick-up truck.
Answer: If you mean the blue wire on the LCD screen, it is a video input switch. The monitor is hooked up with the red wire to 12 volts, black to ground and the blue wire to your backup lights. There are two RCA inputs, one male and one female yellow. The male is video one input. The female is video two input. On the front of the LCD monitor, you can press the "V1/V2" button to switch between these inputs. If you connect the blue wire to your backup lights and use video one for something (like a dvd player), when your backup lights are on, the 12 volts to that blue wire will cause the monitor to switch to video TWO which is where you would connect the backup camera. Shift out of reverse, the backup lights go off and the LCD monitor will switch back to video ONE input. Hope this helps.