Cust states oil pressure drops at idle check of system shows sendering unit leaking after replacing oil sending unit oil pressure now holds at idle but drops as you increase rpms wiring diagram only shows wiring to computer not directly to gauge
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Re: 02 jeep grand cherokee 4.7 eng
Hook up a manifold gauge (mechanical temporary use gauge, used by mechanics) and test the oil pressure. You probably need to replace the gauge. The computer sends info through a printed circuit board behind gauge cluster and sometimes you have to replace the whole gauge cluster.
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From what you just said, it sounds like the problem may be the dash gauge itself. I have only seen one oil pump act like that (mine) .... in that case the pump drive gear was turning on the shaft and slowing down as rpm increased but that is so rare as to be a non issue, especially when the mechanical gauge reads fine. I'd either replace the dash gauge or just install the mechanical gauge permanently on the dash. Doubt if oil in the plug will do that but you can check the plug, clean it and check the integrity of the wires going into it just to be sure.
Oil gauge may be bad, you said you changed the oil sending unit, and tried a aftermarket which worked, so the other option is to have you oil gauge checked. The sending unit may be good but you gauge is not reading proper.
I just had the same problem with a malfunctioning gauge with a very oily sending unit. I went to Oreilly's auto and got a replacement sending unit for $38 and put it in and got the same results you did. I would have 40 psi at idle and it would drop to zero and throw the check gauges light when giving it throttle. I found some posts online that stated to only use official mopar sending units in these vehicles so I gave that a try. Problem solved!!! I now have 45-50 psi at idle and it climbs slightly when under throttle. The sending unit from Chrysler is around $52.
Was the sending unit an aftermarket part?We like to install the original part back into most vehicle, but because of people price shopping, this can cause some issues. If the switch is working properly, the gauge should rise as the engine RPM's increase as you stated. With the key on and the engine off, disconnect the sending unit wire and ground it. The gauge should go to the highest reading, and that checks the wire, and the gauge. I suspect that the sending unit is failed or not the proper one for your vehicle.
Last week my 2001 Grand Cherokee with a 4.7 was dropping below 10 and my "check gauges" light and chime came on. My sending unit was bad. I could see it was bad because oil was getting through the unit and leaking very slow. It's located above the oil filter. Easy fix, but the unit was over $50 and the 1 1/16 special deep socket for sending units was over $10.