If the login is failing because you need a passwordless login by a script, and the script is failing - it is probably because the ADMCHG flag is still set.
Note: passwordless is not recommended. Use the following at your own (companies) risk!
michael@x054:[/]pwdadm test0001
Changing password for "test0001"
test0001's New password:
3004-602 The required password characteristics are:
a maximum of 8 repeated characters.
a minimum of 4 characters not found in old password.
a minimum of 2 alphabetic characters.
a minimum of 2 non-alphabetic characters.
a minimum of 8 characters in length.
3004-603 Your password must have:
a minimum of 4 characters not found in old password.
a minimum of 2 non-alphabetic characters.
a minimum of 8 characters in length.
test0001's New password:
Enter the new password again:
michael@x054:[/]pwdadm -q test0001
test0001:
lastupdate = 1361830098
flags = ADMCHG
michael@x054:[/]grep -p test0001 /etc/security/passwd
test0001:
password = {ssha512}06$ssCPpi0nCu7juMBJ$JyZKPfkmLl0Y.7bgLbVQIw1V.flPaptjEiUXWVpbBPC6Khj9kcprkae4Xd9FYqItjaEPY7kA7lULiVeHS4zl..
lastupdate = 1361830098
flags = ADMCHG
michael@x054:[/]
michael@x054:[/]pwdadm -f NOCHECK test0001
michael@x054:[/]pwdadm -q test0001
test0001:
lastupdate = 1361830098
flags = NOCHECK
michael@x054:[/]grep -p test0001 /etc/security/passwd
test0001:
password = {ssha512}06$ssCPpi0nCu7juMBJ$JyZKPfkmLl0Y.7bgLbVQIw1V.flPaptjEiUXWVpbBPC6Khj9kcprkae4Xd9FYqItjaEPY7kA7lULiVeHS4zl..
lastupdate = 1361830098
flags = NOCHECK
michael@x054:[/]pwdadm test0001
Changing password for "test0001"
test0001's New password:
Setting "test0001's" password to NULL.
michael@x054:[/]grep -p test0001 /etc/security/passwd
test0001:
password =
lastupdate = 1361830487
flags = NOCHECK,ADMCHG
michael@x054:[/]pwdadm -f NOCHECK test0001
michael@x054:[/]grep -p test0001 /etc/security/passwd
test0001:
password =
lastupdate = 1361830487
flags = NOCHECK
michael@x054:[/]
In short, you need pwdadm -f NOCHECK username to disable password checks to be sure you can enter a NULL password, and you will need to enter it again so that the ADMCHG (admin change) flag is cleared after you set the NULL password.
Note: You need to be root to perform the grep -p username /etc/security/passwd command