Oil pressure sensor? Look behind the oil filter, that's the only one I know of with that kind of loom

 

I know what it is. It's s silicon cloth sheath. Sometimes they are a red jacketed sheath (old style), black jacketed (new stye). It's also pegged to the block or head, like a plastic peg of sorts. It's either what's left of your upstream pass side 02 sensor which was my first guess earlier or a little further past that.

Here's how that harness runs , WAIT, I should mention that's only half the wires you have located, still have a grey and another white wire hanging loose in the vicinity...it's a 4 wire harness. Anyway that harness is loop that runs from right to left beginning and ending at both upstream O2 sensors. The harness loops over the trans to engine bulkhead. Directly in the center of that bulk head the harness T's. The T leads to a knock sensor under the intake. This won't be visible but you should be able to feel the T sticking your hand down there by the firewall.
I suggest tracing the O2 harness passenger side from under the truck. Shine a light up in there and track the O2 harness. Keep following, you'll have to run into the break at some point.

BTW- if you decide to meter those wires, keep in mind Black is signal and Grey (once you find it) is ground, a direct PCM ground. The two Whites are heaters. Mighty Mouse wasen't kosher with that harness obstructing his path and went all jack pine savage on it I expect.

 

Thanks jbrew! I'll look tomorrow and I'll let you know!

 

No problem, might have to purchase a new O2. I'd avoid soldering those particular wires since they are sensitive resistance wise. You can though if good at weaving solder or use silver bearing solder only. A fast heat Weller Iron is the best way for automotive IMO. Gets you in and out quickly without making a mess.

Yea, let us know.