04 Ram, 4.7L, zero "oil pressure"
I've got an 04 Ram with about 30k miles on it. Mobil 1 oil since new. I go to start the truck up on saturday and drive it out of my driveway and around the block, while I jockey the position of a couple other cars in my driveway.
When I'm done, I notice that the beeping I've been hearing is not solely due to me not wearing my seatbelt, but also that there is a "check gages" light on and my "oil pressure gage" is reading zero (at this point, I've driven the truck about 1/3rd of a mile while cold, engine sounds normal).
I stop the engine immediately, and check the dipstick. It reads a little low, so I dump a quart in. Start the truck up and still no "oil pressure" (engine still sounds normal).
So, I immediately shut it down, and scrap the trip that I had planned (going to pick up some furniture).
Anyhoo, some internet research shows that there are definitely oiling problems with these engines (plugged pickups, bad oil pumps), but also some oil pressure sending unit problems. I'm hoping it's the sender, obviously.
So my question is, is the oil pressure sender that is shown in the service manual I obtained the only one? It's shown to be right near the oil filter. Additionally, the manual claims that this sender is a variable voltage sender, which outputs a different voltage based on the actual oil pressure. However the behavior of the "gage" lead me to believe (and some internet research seemed to confirm) that the "gage" was actually just an "on-off" display (basically and idiot light in gage disguise). If this were true, then why would the oil pressure sender be a variable voltage output? Perhaps the ECU converts the voltage to a binary output?
Regardless, of all of this, is this oil pressure sensor by the oil filter the only one? Any simple way of testing it, other than hooking up my multimeter and some compressed air?
Any info greatly appreciated.