$oAuto = new Auto("Audi", "A6", 2008, 78000);
2	$oAuto->sellers[0] = "Фирма А";
3	$oAuto->sellers[1] = "Фирма Б";
4	$oAuto->sellers[2] = "Фирма В";

1	require_once("JSON.php");
2	$json = new Services_JSON();
3	$sJSONText = $json->encode($oAuto);

1	{"firm":"Audi","model":"A6","year":2008,"price":78000,
2	"sellers":["Фирма А","Фирма Б","Фирма В"]}

1	{"firm":"Audi","model":"A6","year":2008,"price":78000,
2	"sellers":["Фирма А","Фирма Б","Фирма В"]}

function PostData(){ 
var txtJSON = '{"Items":[{"id":"1538","x":55.788893,"y":37.560405,"addr":"\\u041C\\u043E\с\\u043A\в\а \г, \\u041B\е\\u043D\и\\u043D\г\р\а\д\с\\u043A\и\й \\u043F\р-\\u043A\т, \д\\u043E\\u043C \№ 36, \\u043A\\u043E\р\\u043F\у\с 51","comm":"","color":"#00ff00","owner":"\\u041C\\u042D","type":"0"}]}';
var	DataJSON = $.evalJSON(txtJSON); // создаю объект - все ок....

var PostDataJSON = JSON.stringify(DataJSON);   // а теперь обратно из объекта в JSON строку 

// PostDataJSON получается в виде {"id":"1538","x":55.788893,"y":37.560405,"addr":"Москва г, Ленинградский пр-кт, дом № 36, корпус 51","comm":"","color":"#00ff00","owner":"МЭ","type":"0"}

$.ajax({
        type: "POST",
        url: "http://localhost:43555",
        dataType: "json",		
        data: PostDataJSON,
        success: function() {
                alert("Full");},
        error: function() {
                alert("Error");},
        dataType: "text"
      });
    }

<meta http-equiv="Content-language" content ="ru">
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta http-equiv="content-type" content="text/html; charset=windows-1251"/>

'{"Items":[{"id":"1538","x":55.788893,"y":37.560405,"addr":"\\u041C\\u043E\с\\u043A\в\а \г, \\u041B\е\\u043D\и\\u043D\г\р\а\д\с\\u043A\и\й \\u043F\р-\\u043A\т, \д\\u043E\\u043C \№ 36, \\u043A\\u043E\р\\u043F\у\с 51","comm":"","color":"#00ff00","owner":"\\u041C\\u042D","type":"0"}]}'

var txtJSON = '{"Items":[{"id":"1538","x":55.788893,"y":37.560405,"addr":"Московский проспект д.12...... "

[SRC CSS]var txtJSON = '{"Items":[{"id":"1538","x":55.788893,"y":37.560405,"addr":"\\u041C\\u043E\с\\u043A.........."

var txtJSON = '{\u041C\u043Eс\u043A \u041C\u043Eс\u043A\u041C\u043Eс\u043A\u041C\u043Eс......" 

function JSON_stringify(s, emit_unicode)
{
   var json = JSON.stringify(s);
   return emit_unicode ? json : json.replace(/[-￿]/g,
      function(c) { 
        return '\\u'+('0000'+c.charCodeAt(0).toString(16)).slice(-4);
      }
   );
}

PostDataJSON = {"Items":[{"id":"1538","x":55.788893,"y":37.560405,"addr":"Москва г, Ленинградский пр-кт, дом № 36, корпус 51","comm":"","color":"#00ff00","owner":"МЭ","type":"0"}]}