FS reads in Cover 4

Sorry, I posted this thinking that you wanted reads for cover 3.
For getting a run/pass read have the FS read whatever is easier for him. I start by teaching my FS to read the uncovered lineman. Some of my safeties feel they get a better read by reading the C and OG's, and I don't mind. Once they read pass, they should get their eyes on #2. We tell the FS that if #2 is going to the flat, the FS should look for #1 running some kind of inside route (curl, post, dig). If #1 is coming inside, the FS must get inside and on top of that pattern. The FS can even shuffle a little toward #1. If #2 is going vertical, the FS msut be able to play over top of #1. If #1 drags across the formation, the FS should start to get depth as soon as he sees #2 crossing and look for a crosser.
This is definitely not the only way to do this, but it does work for us.

About three years ago I got this run/pass read form another coach. It sounded too simple, but it worked. I tell all the DB's to read the UNCOVERED lineman to their side. If this lineman fires across the LOS, the play is a run. If the lineman does anything else (pull, cross block, drop), it's a pass. IT WORKS. We would have trouble with DB's keyng linemen who would pull on bootlegs or the tackle who blocks down on Wing-T waggle. We no longer have this problem. I tell the kids that if the lineman pulls and the play is a run, the DB will play it late, but that's OK. I would rather have a DB play a run a little late, than have him fly up and have the ball thrown over his head.