OK looking at the schematic from the Lost Post here is what I would check.
I can only get a blurred version of this page which shows the "Assembly Variable Line Pressure" And PCM so the connector at the top appears to be C106 or C108 and has a Yellow/Orange wire coming out and splitting into three Yellow/Orange Wires at Splice #136?
I would disconnect this connector at the top, disconnect the plug on the Assembly Variable Line Pressure and disconnect plug C4 on the PCM.
This would mean that these three Yellow/Orange wires are floating in free air. I would then check if these wires have any continuity to ground...should not have any continuity!
Then with connectors C1, C2 and C4 on the PCM disconnected and the "Assembly Variable Line Pressure" still disconnected I would check the Dark Green wire, the Yellow Brown? wire, the Yellow/Pink wire and the Dark Blue/Dark Green? wires likewise for any leakage to ground.
These last two wires go to splices somewhere ie. Splice #128? and Slice #138? so if you have the logics you need to find what other components these Splices are connecting to as these will compromise any reading you get from these wires to ground!
If any of these wires are leaking to ground and you cannot find the physical damage you will need to cut the wires off at all ends and replace them with new wires!
I will try find this diagram on the Lost site so that I can come back and hopefully clear up the blurred numbers I am seeing!
Nope...original diagram from this post on Lost is still blurred to me and I do not have 2008 Manuals