How can I tell if the oil pump went bad, or if it's just a m

How can I tell if the oil pump went bad, or if it's just a malfunctioning sensor? 1988 Mazda 323 1.6L ?
When I start the engine oil is at correct level on dipstick, I checked the engine idles just good, then after running for about 30 seconds to one minute, the oil pressure light comes on. I shut the engine off now of course, and after letting it sit for an hour or if I start it again, it'll do the same thing.

Is there a way to tell which it's without replacing the sensor sending unit or removing the oil pan?

When the engine is running,if the pump is full or the pick up is blocked or the oil filter is choked the motor will make a deafening ticking sound.I could propose it could be the sensor although if its not making any wierd noises as these usually go on the 1.6,88 model mazda's.

truck/car mechanic

you can remove the sensor and hook a manual gage up to it, and if it reads good, you know you have good oil pressure,if not you know its the oil pump,either way you,ll have to take off the sensor to hook the manual gage up on it,but its better than pulling the oil pan,and pulling the oil pan would not tell you anything anyway,you have to have it checked with a manual gage to verify it does have oil pressure,good luck on it.