U-Tube is a place to start, but not a complete answer. There are new trucks, 2WD versions, gas and diesel. The location of the sender will vary, some are more buried than others. As the sender is failing the oil pressure will randomly drop to zero and a number of check engine lights will be lighting up along with the alarms that will get your attention. This might be happening when your son/daughter is driving the truck to school, great life lesson for you on how you react to these situations with your child behind the wheel.
Having the truck pulled over ASAP, safely and confirming you still have the required 3 gallons on oil in the sump you start the what if, how come and why not of "old" vehicle ownership. Restarting the truck the gage will/might act like nothing has happened, but not for long. Your child at school and after getting back home, it starts.
Finding the correct answer for you 2005 Dodge Ram 2500, diesel 4x4 is at best a close approximation of what you need to know. I am by my self in this adventure and no I did not take any pictures or video. But what I did do right was remove the inner fender well liner on the driver side. Held in place by a number of 8mm fasteners it helps if you jack up the cab just enough to be able to get some of your torse in the wheel well for the later adventure. Yes, I did place an appropriate axle stand under the frame. Some things on the internet do leave an impression.
Yes, this is an almost no brainer of a repair. How some people are able to get to this connector from on top allows me to think about things that I do not have the time or energy to ponder. I do not have the hand strength to release the connector, or the knowledge of that now 300,000 mile brittle plastic hindrance is going to be removed without much collateral damage. So that is my request, can someone point me at or create a tutorial of how one inserts the screw driver in the connector and releases it without the complete destruction of the darn thing?
I did the right thing. I called a friend who own a shop and he talked me off the cliff and after driving over to his shop and spending less than ten minutes, the connector was off and still reusable for the new sender. Only because I had removed the liner and he could get to it as a straight shot.
Another plus to removing the liner, the removal of that dirt that turns into a moisture trap next to the fender. You know the stuff that rots out the lower corner of the fender. At least on one side of the truck.