Where is the sensor location? Can't find anything anywhere on the location of it.

 

It's right above the oil filter. I can't post pics from this idiotic work laptop, but here's a Google image search that will show you some pics:

Jeep XJ oil pressure sender

Everyone else, please check the date on the post you're about to reply to. This thread is six years old. Some of these people probably don't even have their Jeeps any more.

 

I've also had some issues with my check gauges light, when idle or driving, it usually sits at the max 80 for the oil pump, but every now and then while I'm driving it'll drop really low, and if I lay off the gas or start breaking, it goes up again eventually. I drive a 99 Cherokee sport, and the oil is full, any thoughts are much appreciated.

 

You can verify your oil pressure using a manual oil gauge, but most likely it's a bad sender, bad wires going into the connector to the sender, or both.

It would be extremely unusual for you to actually have 80 psi of oil pressure. Maxing out at 80 psi is more likely a sign that the circuit is shorting to ground somewhere. It can do that inside the sender, or it can do it if the insulation on the wires has been damaged. Damage can come from chafing, but it can also be caused by oil leaking through the sender and connector and eating the insulation right off.

I would inspect the wires for damage first. If you have a helper, get them to start the Jeep and watch the gauge while you wiggle the wires to the oil pressure sender. If you can make the gauge change by wiggling wires, you need to get a new connector and pigtail (usually in stock at local parts stores) and splice it in. If you see oil on the wires, you probably need to replace the sender as well. If wiggling wires doesn't make any difference, it's probably the sender itself that has the short inside it, so you'll just replace it.