our son is driving a dodge ram 1500 and the dash light for the airbags goes on and stays on

Did you buy it new? If the connectors are under the seat or seats tightened all the connectors under seats. The year was not stated but the one I have seen are under the seats, May use some contact cleaner (Electrical Board cleaner) and then use some dielectric grease on connectors before plugging back together.

ok if you are talking the truck in for a Recall then they can not charge you to look at the truck or to fix it

well the guy is kind of right almost all ways there is a Weight sensor under the seat so that the truck knows if someone is actually sitting in the seat so it knows to arm the air bag if there's no weight in the sea the truck will not arm that airbag so that it will not deploy in an accident because there's no one there but most of your abs system is in the - but as I said The guy is half right there is electrical connections under the seat for the weight sensor Only but that is good advice to clean the connections for the weight sensors and see if that clears up the problem

The reason the light comes on and stays on is because there is loss of continuity with the electrical System or there is a bad or deployed air bag or one is missing or one of its sensors is bad or bad/loose connection, bad computer and under the seat is most often affected, could be others but most likely to get dirt, drinks, ect in the connection, worth checking before spending $100.00. Put it blunt your comment of taking it in no charge for recall is not mechanical advise neither is he's half right. I offered real advise, as the question states all recalls have been performed which means its not under recall anymore, so they get charged fro the visit. If its a loose connection, well that takes care of the need for a $100 visit.