PCM Signal Return???

[nicmartim]

Update:

I got my wires crossed (figuratively speaking). The wire in question does NOT output the 5.5 reference voltage to the 3-wire sensors like I theorized above. That wire is #90 and is called the VREF (fittingly enough). That wire checks out just fine on my PCM. The wire I have issue with is grey/red and I am not certain the color scheme of the VREF, but I am certain it is NOT the issue. Thanks and hope somebody has some input shortly.