i dont know about them "going bad", but they can get screwed up. the little chip in the key can sometimes wiggle loose in there...it is possible for them to go bad though, i think any type of electronics can fail like that at some point, but given that your truck is a 99, i would think it would last a little longer. odds are yours just came loose inside the key - but i guess it is still possible for it to have gone bad.