Oil Pressure Gauge Issue

Well I was driving the other day and noticed that my oil pressure gauge was spiked. I thought maybe I somehow broke the gauge. I had an extra one laying around so I threw it in. Started up the Jeep and the needle went right back to the same spot. It is sitting right above the little screw on the right. The rig is running normal. Why is it doing this????

The wire is either chafed and grounding out, or not making contact at all.

The reason I offer two extremes is that in 91 Jeep (Chrysler) changed the polarity on the gauges, and I don't recall off the top of my head which years go which way.

Start the engine, put an assistant in the driver's seat, then remove the wire from the sender. Se if the gauge drops to zero. If not, stick a length of jumper wire in the connector and ground it. If it didn't go to zero with an open circuit, it should go to zero with a short circuit. Assuming the gauge zeroes from one of these tests, the gauge is okay and you should first check the wire, and if you don't find a problem then replace the sender.

where is the sender located??

Passenger side of the engine, just above the oil filter. Has a single wire going to the aft end of it.

The senders frequently go bad, and the usual symptom is the pressure guage spiking, just in case Eagle's bad wire idea doesn't pan out.

Fred

In my case ('01) the gauge reads backwards: full scale with low pressure, dropping to mid-scale at 2-3KRPM. Sensor was changed, and made no difference. The gauge test reads OK, so it must be either the PCM or an inverted wire (harness seems to have been tampered with). The FSM shows the connector and the wires, but it's not clear to me which way to look at it. (which is left or right when I look at the sensor). Any of you guys can clear this for me?

jldiaz said:

In my case ('01) the gauge reads backwards: full scale with low pressure, dropping to mid-scale at 2-3KRPM. Sensor was changed, and made no difference. The gauge test reads OK, so it must be either the PCM or an inverted wire (harness seems to have been tampered with). The FSM shows the connector and the wires, but it's not clear to me which way to look at it. (which is left or right when I look at the sensor). Any of you guys can clear this for me?

Click to expand...

The FSM diagrams are shown "head on" so if you're looking at a harness connector diagram it should show what you see when you look at the business end of the connector when it is unplugged.

91 Jeep Project said:

Well I was driving the other day and noticed that my oil pressure gauge was spiked. I thought maybe I somehow broke the gauge. I had an extra one laying around so I threw it in. Started up the Jeep and the needle went right back to the same spot. It is sitting right above the little screw on the right. The rig is running normal. Why is it doing this????

Click to expand...

I had the exact same problem and turned out that the sender wire was shorted. I verified it by simply moving the wire. The sender wasn't that expensive as I recall, so I just replaced it as my XJ is nearing 200K. For anyone wanting to help prevent this from happening in the future just install a short piece of loom over that wire.