Oil pressure drop when stopped

[Goatman]

You should be able to put a T-fitting (brass) in line with the sensor and plumb in a new line to a new gauge mounted in the dash area somewhere. When I was young everyone got a 3 gauge setup mounted (mostly) to the bottom of the dash near the center that had volts, oil pressure, coolant temp. Don't see that much anymore, probably 'cause it looked like . But back then all the 'cool' guys did it.

 

[Scout425]

I finally got around to replacing the oil pressure sending unit/switch with MOPAR part# 05149097AA. I purchased mine from a local dealer for $58 but a quick internet search shows results for around $30-40.

While the new sensor seems to have helped, it did not fully resolve the issue. With the limited driving I did to test it, ~20 miles, the oil pressure only dropped twice and only to about the 1/4 dot on the gauge. I don't recall it doing that in the past but now it does not drop far enough to set off the alert chime. In more recent video on youtube, a guy had the same symptoms and may have resolved his issue by cleaning the connectors at the PCM. Prior to that he replaced the switch with a duralast unit only to have the same symptoms reappear. Cleaning the PCM connectors will be my next step if the chime returns.

 

[Alemonkey]

Worst case, if you rule everything else out, replacing the oil pump isn't a horrible job. I replaced the one in my '97 4.0 a few weeks ago with a standard (non high pressure) Melling pump. It used to get down close to zero at idle with a hot engine and occasionally sound the alarm, now it never falls below 20. I'm sitting at 150K on the odometer.

 

[Scout425]

Steps taken so far:

Replaced Oil Pressure Sending Unit/Switch with OEM. No improvement.
Changed oil and installed OEM filter. First 100m seemed to have less warnings.
Spayed out PCM and sending unit connections and applied dielectric grease. No improvement.

I've seen numerous posts identifying the sending unit as the culprit but far fewer with steps to take when replacing the switch does not resolve the issue. Hopefully I can add to that and also have some questions answered by those more skilled than me. Below is a snip of the FSM troubleshooting steps.

This specific table is for the 2.4L since the 4.0 only had steps for low pressure and not another for dropping.

Here is the 4.0 troubleshooting steps for reference. Im hoping I only ended up with a new faulty sensor. We'll see.

I picked up a manual pressure test gauge and plan to check for the recommended 13psi at idle today.
Spitballing here: Assuming I have adequate pressure, I was curious if there was a way to check the wiring harness for issues to rule that out. I'm a novice with a multimeter so my question for the group is if I would be able to check for continuity and resistance between the PCM and sensor? Below are thumbnails illustrating the PCM and Sensor's plug. Looks like I would be using CAV 1 on the switch and CAV 20 on the PCM. I also saw that the switch is supposed to be supplied with 5V, I plan to verify that as well.

I don't believe that the wiring is my issue, just want troubleshoot everything I can that is free before moving on to more expensive steps.