For more information about Robert's Rules, check www.robertsrules.com. Also, a book that I like is "Robert's Rules in Plain English" by Doris P. Zimmerman. You can pick up a used copy for a whopping $3...!
The situation you are describing is why typical bylaws include a statement establishing the source of their parlimentary authority, usually Robert's Rules of Order. That way, most procedural issues are covered (by the established and time-tested rules in Robert's Rules) without having to list them all in your bylaws. RRO would not allow a motion to pass without a vote.
They way we vote is someone makes a motion and then someone seconds the motion. Then we say "all in favor?" and count the raised hands of those in favor. Then we say "all opposed?" and count the raised hands of those who are opposed. obviously whichever had the most hands raised is the outcome of the vote. I assume this is what you are looking for and if your bylaws are vague in this area you can ammend them to reflect the way you want a vote to be held.
This is my first year as an officer in our PTO. The problem started last year with our voting procedures. In the past, the members would make a motion then second it and the item would pass. I believe this is not the proper way things are done. A vote of the members was never taken. The new officers tried to get the item (which involves money) a re-vote, and were told that the money cannot be taken away. How can the problem be fixed so it is not an issue?
Our by-laws are very vague on the issue.