geez, ok vtec will only engage if its warmed up enough,if you have enough oil pressure, if the solenoid is good and pressure switch and if the ecu is good, you can hook it to a switch but that's still not true vtec because all that does is lock the cam it does nothing to the fuel maps like real vtec does.and also real vtec will only work after your going 20mph if you have a single cam sometimes you wont even hear it change over but on a dohc vtec motor you should be able to hear it change over depending on if its stock or tuned
This is all you need to know! Very simple but to the point! Remember this( K.I.S.S.) aka (keep it simple stupid)
No offense of course not directed at you personally. Just start simple and work you way up. Don't tear the head down then find out it's a bad soleniod or cloged oil journels.