To return the Full request and Full response from eWay, open the bindings panel, click the plus button and select eCart -> Checkout -> Local Checkout Response. from the gateway list, select eWay XML.
in the bindings panel, expand the eway binding group and add the Full request and Full response bindings to your page.
Another way to see the errors, is to write the entire contents of the session to the page:
<pre><?php var_dump($_SESSION); ?></pre>