Ajax calls resulting in an error[object Object] - php

Question

I am getting an error[object Object] while trying to pass a value through ajax calls. I am using jquery selector to get value of checkbox. And trying to pass it through ajax so that I can get only the checkbox value that I have selected. But getting an error. Thanks.
Here is my code:
dashboard.php
if($param['aktion'] == 'save-widget-vehicle')
{
$page['register-fahrzeuge'] = array(
1 => array( 'Fahrzeug','aktiv',$page['script'],''),
0 => array( 'Edit-Fahrzeug','enabled',$page['script'],'',''),
);
$opts = !empty($param['filterOpts']) ? $param['filterOpts'] : array();
$tmp = array();
foreach ($opts as $opt) {
$tmp[] = '"'.$opt.'"';
}
$query =
'SELECT Fahrzeuge.dsnr,name
FROM Fahrzeuge
INNER JOIN ohne_fahrzeuge ON Fahrzeuge.dsnr = ohne_fahrzeuge.dsnr
WHERE Fahrzeuge.name IN ('.implode(",", $tmp).')';
$result = mysql_query($query, $myConnection);
$data = array();
$html = '<table width="538" cellspacing="0" cellpadding="0" border="0">
<tr>
<td>
<div>'.CreateRegister($page['register-news']).'</div>
'.CreateMessage().'
<div class="cont-liste-verlauf register"> ';
while($row = mysql_fetch_array($result)){
//$news_result = $fahrzeuge['name'];
$html .= '<table id="fahrzeuge">
<tr>
<td>
'. $data[] = $row .'
</td>
</tr> ';
}
$html .= '</table>
</div>
</td>
</tr>
</table>';
$return = array(
'status' => 1,
'html' => $html
);
echo json_encode($return);
die();
$param['aktion'] = 'get-widget-vehicle';
}
dashboard.js
function getFahrzeuge() {
var opts = [];
$("input[type=checkbox]").each(function () {
if (this.checked) {
opts.push($(this).attr("id"));
}
});
return opts;
}
function saveFahrzeugeWidget(opts){
if(!opts || !opts.length){
opts = allFahrzeuge;
}
$.ajax({
type: "POST",
url: "ajax/dashboard.php",
dataType : 'json',
cache: false,
data: {filterOpts: opts, 'aktion' : 'save-widget-vehicle'},
success: function(data){
// $('#fahrzeuge').html(makeTable(records));
$('#fahrzeuge').html(data.html);
},
error: function(data){
alert('error' + data);
}
});
}
$('#fahrzeuge .butt-rahmen').live('click', function(){
if($(this).attr('id') == 'submitId')
var opts = getFahrzeuge();
saveFahrzeugeWidget(opts);
});
var allFahrzeuge = [];
$("input[type=checkbox]").each(function(){
allFahrzeuge.push($(this)[0].id)
})