Check gauge light on and oil gauge to 80 - 2000 Jeep Cherokee

The first thing to do is check the pressure with a mechanical gage to see if the pressure is that high. Then you can rule out the pump or other problems.

Check your oil level

The computing system on your vehicle has no safe mode for running low on oil . The only thing that will happen is the check gauges light will come on.
The oil pressure gauge is an analog device that is located in the IPC. The oil pressure gauge is operated directly by the oil pressure sensor circuit. As the engine oil pressure changes, the resistance of the sensor and the current flow in the oil pressure gauge changes. The current flow in the oil pressure gauge causes the needle to move in order to appropriately display the engine oil pressure. A sensor resistance of 1ohms will display as 0 kPa (0 PSI) and a resistance of 88 ohms will display as 80 kPa (80 PSI ). The IPC also monitors the oil pressure sensor circuit and interprets the current flow in this circuit in order to determine when the engine oil pressure is too low. If the oil pressure is too low, the check gauges tell tale will turn on. The oil pressure sender is located on the left side of the 2.2L. The 4.3L engine, oil pressure sender is located at the top left side, near the distributor/high voltage switch.
Try disconnecting the battery cables an hold them together for ten minutes , reset ECM !

Remove the oil sender unit and fit a pressure gauge , start the engine and check pressure, seems odd the oil light and pressure gauge both showed a fault at the same time, perhaps the oil pump relief valve stuck open for a short time.

you must need to RUN the scanner/computer for easy diagnostic and fix it. See the diagram attached, and get some idea. God bless you

Another gauge needs to be connected to the car to check that oil pressure sensor or the gauge itself is not the problem.

If an independent gauge shows the same readings I would suspect a sticking oil pressure relief valve.

Hi
have your oil replace with new and make sure it is the proper weight. In cold weather old oil gells up making thiker once it warms up the pressure will go down but is not protecting you engine.

the oil sending unit could be out or the pressure guage is malfunctioning is the service engine light on?

Have your oil sending unit checked, this part is not to expensive

That is probably a defective oil pressure gauge or a broken oil pressure sender, it reads 80 psi just because that is the maximum value allowed.

Pressure can be verified by reading it with a gauge tool.
If you really have pressure over 70 psi when engine is running then start replacing the oil filter, and check that the oil lines from pump are not obstructed, if there is nothing in there then replace oil pump.

If instead the gauge reads 80 with engine off, that is a defective pressure gauge.