How does evap system bay test work?

[Davidsnap]

Hello! First post. I saw a similar post to the one I'm about to present but with no answer. I have a 07 Tahoe. Trying to do a system evap bay test. It hasn't hit that monitor aka pid yet but all others. All it says is waiting for purge enable please wait. First of all how long do I have to wait for, second every time I do the "running test" it fails about 3 seconds. Any explanations?

[ephratah service center]

you should be able to check and see the abort reason there should be a pid that is displayed abort reason