Truck won't start, relay clicking.

Actually if you follow the wireing right out of your firewall, you will come to a sensor, chances are the male end is missing, go to your local hardware store and let them know your problem it's quite common with those trucks from 91-95, what it does is it's like a brain it will run good without it, but it works your truck overtime, so eventually it starts giving you hell and then just quite's. Good luck