I have just put in an indash 7 in lcd in my car and it works fine when in the acc position but doesn't work when car is on. how can i make it work when the car is on?
If it were wired correctly, the screen would run when the car is started.
Now, you've levt out some key details, namely:
What make/model screen do you have?
How did you wire it up.
Simply posting "My screen isn't working right" isn't going to gain you a lot of assistance because you're not providing any details to enable anyone to help you.
Oh, and quit crossposting!
the screen is a motorized 7 in screen, don't known make/ model. it is wired from the dvd player through a little fuse box. with four wires red(acc), yellow(batt), Blue(back) and green(ground)
Judging from your response, I'm going to guess that you didn't wire this piece of equipment. Either you paid a friend or a shop to wire it or a friend/relative/coworker did it for you.
IF you did the wiring yourself, you'd be able to provide lots more information than "through a little fuse box".
YOu say that the yellow goes to the battery and the red is accessory. Wehere, specifically, do those go? Does the yellow go to the battery or some other constant 12v source in the car? What liine or harness did you tap into for the red (ACC) wire? Perhaps the green wire (which you have wired illegaly in order to bypass teh emergency brake cutout, by the way) isn't supposed to be a ground, but some other function.
As you can tell i don't have much idea of what wires are which but i am guessing. i did actually get is professionally done i have already had to connect some input and and output wires together which the guy missed. all the wires that are coming in to the screen are from the dvd player. they feed to a box which has a fuse in and then they lead on to the screen
OK, this isn't something you want to guess at, because you could completely screw up your equipment, your car or yourself.
You have two options:
1) Take it to a professional who knows what they are doing and can correct the problem. A local car stereo shop (not a BestBuy or other chain that handles all manner of electronics) should be able to correct your problem.
2) Learn to do it yourself. While mp3car has all the information about your screen and how to get it wired properly, it's up to you to figure out about your vehicle's wiring. A great resource for this is http://www.the12volt.com . They will likely be able to provide wiring diagrams for your year/make/model of vehicle as well.
Get a voltometer too. Very useful.
1996 Accord Ex Carputer
Soon to come 2008 WRX 5-door Mac-carputer.