Ideally you need to see what your requests (and the responses) look like on the wire, using something like ssldump. Here's how I do it, first, reduce the strength of the SSL/TLS cipher strings used for iControl connections, save and restart the httpd;
tmsh modify sys httpd ssl-ciphersuite NONE:RC4+RSA
tmsh save sys config
tmsh restart sys service httpd
Then use ssldump to capture live traffic;
ssldump -dXnqi eth0 -k/config/httpd/conf/ssl.key/server.key
And that's it, you should be able to see all the XML calls back and forth.
Note this will also capture any traffic generated by management GUI activity so best to ensure nothing is going on there.