I hate to say it but you might probably be best off taking it in..... From previous experience i have learned that the Airbag system is pretty complex. Once i tripped the light reinstalling the front bumper (on an 01 accord)(would have tripped the bags had the ignition been on, luckily just tripped the sensor so the system detected a fault). another time the light would go on and off intermittently so i took it in and was informed that the seats had vacuum sensors in them and if you were not sitting properly(or had something on the seat) in the seat it would trip a fault and disable the system so that the person sitting in that seat wouldn't get hurt more (airbag not making contact at the right point of the body). I don't know if the system on your truck is that complex or more complex, but there are a lot of places to start. It might just need to be rest. A good mechanic probably wont charge much to reset it if anything at all.