my brother in law has a 96 neon, got into an accident recently...he fixed the car, it ran for about a week or so, then wouldn't start the other morning....he got the code for it, P1682, which means that the charging system voltage is too low...replaced the alternator with a brand new one, it still won't start....any ideas on what else to check??? father in law thinks it's the pcm

 

Could very well be the PCM or a new battery is in order.