5 volt reference same as signal voltage

2002 duramax 6.6 L diesel engine, 5 volt reference and signal voltage same 5 volts, fuel pressure regulator and fuel pressure sensor both at 5 volts, engine starts but real ruff idle with a code po193  high fuel pressure and high voltage, have official gmc manuals but terrible wiring schematics. I know fuel pressure and engine speed follows each other so at idle sensor signal should be around 2 to reduce fuel pressure but both a 5 volts. Where do I get a wiring schematics that shows the 5 volt reference circuits and can 5 volt reference short to signal voltage or ? Where to start

charm.li/Chevrolet/2002/C%202500%20Truck...Code%20Charts/P0193/

charm.li/Chevrolet/2002/C%202500%20Truck...l%20PRESS%20Sensors/

charm.li/Chevrolet/2002/C%202500%20Truck...e%20Sensor%2FSwitch/

The flowchart for p0193 highly suggests it's a pull-down circuit design for the middle wire, the signal wire. Therefore, with the sensor disconnected it's normal to have 5 volts on this wire. It is the job of the sensor to pull down this voltage and it needs a good ground to do that. The ground, or low reference as referred to in the diagram, is a clean (which means NOT NOISY) ground that comes directly from the computer. Make sure when the key is on engine off ( KOEO ) and the sensor is still connected, this wire voltage stays close to zero volts - 50 millivolts or less. A missing ground to a sensor will show 5 volts on all 3 wires with the sensor connected.

How to determine which is the 5v reference and which is the signal? With your multimeter, one of them will usually read closer to 5V, whereas the signal wire will usually show slightly less. If in doubt, with the meter still connected, try pulling the signal wire down to ground through your body. Lick your finger touch one end to that wire and put your other finger to a ground, or bare metal surface. The reference wire will hold steady - that's its job - the signal wire will waver because it’s a weak sauce 5v. If you have a test light that draws a quarter of an amp that may  illuminate your test light dimly should it find a 5v reference but it won't on the signal wire. You can also use the test light to pull the signal wire down to ground and see if the scanner PID will reflect a lower pressure/voltage.

can 5 volt reference short to signal voltage or ? Where to start

If you think this is what you have, disconnect battery, disconnect pcm, disconnect sensor and ohm check signal wire and 5v reference wire at connector. The signal wire is a dedicated wire back to the computer and is not shared with any other circuit. If you take the sensor and pcm out of the equation the DVOM should show OL.

Interestingly the flow chart has a different way to test for a short to 5v ref on the signal circuit:
KOEO, sensor unplugged, measure the current between the FRP sensor signal circuit and ground circuit at the FRP harness connector with a DMM. If the current is more than 10 milliamps, it's shorted to 5V reference, if it's less than 10 milliamps its normal.

Neato. Definitely faster than unplugging the computer.