Most likely a worn electrical ignition switch. There is a steel rod that runs from the key cylinder to the electrical part of the ignition switch. As you turn the key the rod is pushed down and activates the different areas of the electrical switch. The switch is usually mounted on the top of the steering column with four small screws. It also has some amount of adjustment. It's possible it is just loose and/or needs to be adjusted to work properly. You'll probably have to take out the bolts holding the steering column up.. usually two bolts but maybe four. Let the steering column drop down to gain access to the switch.
Maybe you worked your truck a little to Hard. EASE UP on driving just a bit.
the truck driver wont be there at the start but will be there later
What type of truck is this?
Daytime running light module may be the problem
my ford f-150 truck alarm wont shut off
2004 mercedes truck wont start sometimes. Why
The batterie cables are usually the easiest
It could be the keyswitch or the starter could be wired wrong.
It wont allow it to start or sometimes may start but die when you press on the accelerator.
check the microchip in the key if its missing or bad the truck wont start
It would seem that it is not properly connected.
Help truck wont start