If I arm my alarm (stock, 2003 3.0 if it matters), the alarm will go off.

Sometimes the alarm is loud, sometimes I can barely hear it. Sometimes I can disarm/arm and it'll stop and beep once as normal.

Sometimes the alarm will continue to go off and pushing buttons does nothing.

Is it the key's battery going out or something? If so, do I change it out or do I need to take it in? If not, whats the deal?

I read another post that mentioned the interior motion sensor but mine is disabled... I think.

Thanks