Chrysler Repair: 1995 LeBaron 3.0 V-6: False High Oil Pressure On Gauge, value resistors, pressure relief valve

Question
The reading on the instrument cluster gauge is alarmingly high--half to three fourths of range.  I checked actual pressure with external gauge and it runs roughly 80 PSI on start up and settles down to roughly 15 PSI when engine is warm. Can oil pressure gauge be recalibrated? I also installed new oil sending unit with similar results as old one.

Answer
Hi Tim,
Most owners are concerned when the oil pressure gauge reads too low. But in any case, it appears that the pressure relief valve in the oil pump is ok because it should open somewhere between 71 and 85 psi. On the gauge itself, the manual gives the resistance reading you should measure between the sending unit pin and the ground pin at the gauge when the engine is running as follows: 100 ohms when reading L, 63 ohms when reading Low Normal, 30 ohms when reading 3/4 of Normal, all these with a tolerance of +/- 4 ohms. You might want to check the resistance between the gauge ground pin and the ground pin at the harness connector just in case you have a cold solder joint on the circuit board.
I would be inclined to not worry about it as you know now what the needle points to when you have 80 and 15 psi values. Both those points are well within the normal limits of operation of oil pressure so why bother to try and get a more accurate appearance of the needle? The real issue is when does the psi drops below 6 psi at idle or 35-75 at 3,000 rpm which are the engine specs. You will know when/if you reach that point even if the gauge is nominally reading high. I suppose you could fiddle with putting low ohm-value resistors in the circuit to see if you can get it closer to true, but recall that many car makers don't have such a gauge, just a warning light.
Let me know if you try that approach and what worked for you, please.
Roland