Which model truck and I will try and get one, turbo or non-turbo, what transmission?
I have run in to that problem, more than once, and almost every time the cause was the wiring harness rubbing and shorting out allowing the circuit to backfeed or a relay in the start circuit that went bad and was backfeeding.
Oh, and once where a bonehead had plegged the male and female connectors in the circuit for the non-existant CTIS solenoid. The harness on a M1114 has the connections just sitting there, under the park brake/shifter. If somebody has been messing around down there and plugged those in, it will cause that problem the next time it is started.