Yes, they'd have you arrested for doing it, it is called stealing. It isn't quite as bad as regular stealing, however, since you had intentions to later get it out of pawn and continue making your payments as if nothing had ever happened. But still, when you give something to a pawn shop, there is no certain guarantee you will be able to get it out of pawn again, and in a certain time frame, so that's why I say it is still really bad that you did it because it's possible their stuff could have been gone forever if you couldn't get it out of pawn. And with regular stealing, it's normally possible for the police to recover the stolen goods, but if they were pawned and then sold to someone, it could be a lot harder, or maybe impossible, for the police to recover those goods.
The rental place has no way of knowing you did it if you don't tell them and you keep making the payments to them, and you get it out of the pawn shop asap. They can only know you did it if you tell them, or if you don't make your payments and thus they come to see you to get their stuff.
It would have been better to not have pawned it and to have just been late on the payments and gotten a job and then once you got your first paycheck use it to pay the overdue balance. That way you wouldn't be stealing by putting it into pawn. Another better option might have been to borrow the money and then get the new job. Or, maybe you could have found some sort of little job(s) like babysitting, walking people's dogs, something to bring in extra money to get by for awhile. Or work through a temp agency. Or even get a job at a fast food restaurant or something.
Anyway, I'm so glad you found a job, as this should solve your problems, and you can continue making your payments, get their stuff out of hock, etc. If I were you I wouldn't tell them what happened.
If for some reason they do find out you pawned the stuff, you might be able to keep yourself out of jail if they are sympathetic and understanding and if you get it out of pawn right away and continue making the payments, but yet they might not like you very much or not trust you after that.
This is how a lot of people end up in a life of crime....they are financially desperate and they steal in order to get themselves out of the bind, but they either get caught by the police, or they continue to have financial problems and so have to steal again to survive, and it becomes a vicious circle.
You are learning a valuable lesson here, so retain the lesson and don't do it ever again, no matter what. You are lucky you can hide that this has happened this time, but if you do something like it again, you may not be so lucky next time.
Forgive yourself, clean up your act, get more financially stable, and you'll be okay. Don't get overly paranoid about it, or wallow in guilt and fear, just stay optimistic and expect it to all be resolved.