You mean the "choke" light?
Do you have gauges? If so, check the oil pressure.
If it is reading low, stop driving the truck (like right now). Don't run the engine until you are sure you have oil pressure.
On trucks with gauges the choke light is really more of a low oil pressure warning alarm than anything else. I mean really, who needs to know if the choke heater is getting juice. As long as the engine warms up normally - that's an indication that it is working.
Here is what I'm talking about:
The choke heater coil (that begins to open the choke as soon as the engine starts) gets it's power from a switch that is activated by engine oil pressure.
As soon as the engine oil pressure gets up to 10 psi, the switch closes and the choke light should go out.
The may be other reasons for it to stay on (like a disconnected/broken wire, faulty pressure switch, or a blown fuse).
But if the wiring and switch are okay and it stays on it means your oil pressure is less than 10 psi.
It is most likely a bad switch (or the connector fell off the terminal on the choke heater) but you would be smart to find out.
If you have an oil pressure gauge and it reads a normal pressure (30 - 60 psi) you can probably keep driving and fix the choke electrical circuit whenever you get a chance.
If it turns out to be an electrical problem come back to the forum and someone will walk you through the troubleshoot and repair process.
Good luck and welcome.