2 Answers

We used to call those 'idiot lights'.  I am surprised that you don't have an oil pressure gauge on that truck. Gauges are always better than lights, when it gets to a point the light comes on, the problem has been going on for awhile, a gauge will let you see the drop in pressure.  Simple things, have you changed your oil?  have you checked your oil level.  My son a few years ago thought all you had to do was just add oil when it gets low, little did he know that old sediment/sludge was circulating the system, after a period of time, his oil pump gave out and he blew his engine., he added oil every time the light came on.

The oil PRESSURE Light will illuminate when the engine stalls or the oil PRESSURE drops to an unsafe level.

Never allow the engine to RUN if the oil PRESSURE Light has illuminated,.or you will destroy your engine

Have it checked by a technician at once, WBMS