Oil Pressure Suddenly Reading in High and Low Ranges

NO , there is not a fuse just for those two thing's ! There are two power supply's for the whole insturment cluster . You could need a new cluster or the ECM isn't sending this info. to the cluster . Could have DTC'S - diagnostic trouble codes stored in the PCM or the insturment cluster . Without knowing how this works (insturment cluster gets it's info.) Your best bet , take it to a qualified repair shop that has the knowledge and test equipment to diagnose this problem.
Engine Oil Pressure Gage
The instrument panel cluster (IPC) displays the engine oil pressure as determined by the engine control module (ECM). The IPC receives a serial data message from the ECM indicating the engine oil pressure. The engine oil pressure gage defaults to 0 psi (0 kPa) or below if:
• The ECM detects a malfunction in the engine oil pressure sensor circuit.
• The IPC detects a loss of serial data communications with the ECM.
For the 4.2L LL8, the ECM uses an engine oil switch that is open when the oil pressure is normal and closed when the oil pressure is low. At normal pressure, the engine oil pressure gage will display 275 kPa (40 psi). At low pressure, the gage will go to 0 kPa and the low pressure warning will be displayed in the driver information center (DIC). At high pressure, the gage will display 551 kPa (80 psi). Any values between these three values are calculated values determined by the ECM.

Voltmeter
The instrument panel cluster (IPC) displays the vehicle voltage based on the information from the body control module (BCM). The IPC uses the serial data information from the BCM to provide a voltage level indication on the voltmeter.

DTC P0521: Engine Oil Pressure (EOP) Sensor Performance

DTC P0522 Engine Oil Pressure (EOP) Sensor Circuit Low Voltage
DTC P0523 Engine Oil Pressure (EOP) Sensor Circuit High Voltage

Volt Gage Inaccurate or Inoperative
2
Install a scan tool.
Turn the ignition ON, with the engine OFF.
With the scan tool, perform the instrument panel cluster (IPC) gauges output control.
Does the volt gauge move up and down when commanded?

28-32 PSI low side, high side can go as high as 350 PSI depends on the heat load and humidity. The low side pressure is the important one.

Measure your oil pressure with an external gauge. The transducer (sending unit) has high failure rate, you may not actually be running low pressure.....

try sensor first ( its much cheaper ) but wile you have the sensor out screw a manual gage in the hole and get an acreate reading on the oil psi.......KEEP IT CLEAN SEE YA

somewhere around 1.6 pounds (1lb.14ounces) of R134a if system is evacuated and 3 ounces of oil with new compressor.
keep pressure on the low side around 34-37psi & it should blow snow. Below are normal car AC pressure readings with 134A.

• Normal readings on high and low side with AC OFF (static pressure) – Depends on outside temperature, but normally is between 80-105 PSI
• Normal low side reading with AC on high speed and MAX & engine at 800-1000 RPM’s – Ranges from 25-35 PSI –
• Normal high side reading ranges from 200-350 PSI

Don’t assume that if adding little Freon is good that adding a lot is better! Overcharging just a little can decrease the performance of the system and possibly damage the compressor.
DIY recharge kit:
With the AC on the coldest setting, use a thermometer in a middle vent. Normal vent temperature readings will vary depending on the (ambient) outside temp. The vent temperature should range from around 42-55 degrees in my experience. If normal gauge readings are obtained and the vent air is cold – STOP don’t overcharge the system.
Thank you for using fixya and be safe.

CHECK OIL PRESSURE FIRST.DEPENDS ON THE ENGINES SIZE JEEP OIL PRESSURE RANGES FROM 25 PSI TO 37 PSI.IF PRESSURE CHECKS OUT GOOD GAUGE COULD BE FAULTY.IF OIL PRESSURE IS STILL TOO HIGH.YOUR OIL TOO THICK.OIL RETURN HOLE STOPPED UP.OIL PUMP PRESSURE REGULATOR STUCK CLOSED.

At 2000 RPM a new GM engine should be close to 45 psi for oil pressure. It'll drop to mid or high 30's at idle. Hope this helps.

CHECK GAGES light (1) indicates a potential engine failure(low oil pressure, low coolant, coolant overheating) has occurred.
· Check gages and shut down engine. Gages should read as follows: Oil pressure 5 to 10 psi (34 to 69 kPa) at idle; Water Temp gage below 230 degrees (110 C).
· Check engine oil level (Para 2-11) if OIL PRESS gage indicates low reading. Check coolant level (Para 2-11) if Water Temp gage indicates high reading. Notify Unit Maintenance if levels are low.

If CHECK ENGINE light (2) is on, check engine oil pressure gage (3) and water temperature gage (4). If both indicate normal, proceed with mission and then notify Unit Maintenance. If either one does not indicate normal, stop engine immediately and notify Unit Maintenance

yes it might work if u flush it, give it a try

At idle, at operating temp is there any ticking from top end of engine? Are there any knocking noises brom bottom end?
If no noises, change oil and add some Marvel oil to clean out galleys. If that dosent work, change oil pressure sendingf unit. Also, if you have a mechanical oil pressure gauge, hook it up and take a direct reading. Oil pressure (in any vehicle) at idle should NEVER be less than 15psi. Generally in 4.0 jeep engines it's never less than 30, with a high reading at driving rpm of about 40-60! (but, you did not mention what engine you have)