Scott, no point going factory on the security system, even if it is still available from Toyota. An aftermarket one will do just fine. I have a Prestige 150 system and it works very well. Check out www.audiovox.com if you want some info on it. Other brands will also be fine. As for the problem with your changer, I really don't know. It seems to be a problem with your deck, since the changer draws its power from there.