Cadillac: 1997 Catera, oil pressure switch, oil pressure sending unit

Question
Hi, I have a 97 Catera, today the oil gauge went way up and way down when I take off and stop.  The light and the warning buzzer went off when I stopped.  When I took off the pressure went back up,but when I slow it goes back down, so low that the buzzer goes off. Is this the Oil Pressure sending unit? or the oil pump? The oil is full. the oil pump?

Answer
You need to put an external oil pressure gage on the engine oil port and drive the vehicle and see if the gage fluctuates errattically. If it does, Most likely oil pump or the oil baffle in the oil pan came loose.

If the pressure on the external gage remains OK, replace the oil pressure switch.