Darren,

What ecu and switch are you using as the ford workshop info i have states
volts, is 2wd ecu is 4.5 to 5volts at idle closed throttle, and 0.5volts open.

and 4wd ecu l8 is backwards ie 0.6 volts closed and 4.5 to 5.5approx open. PFO1 IS 2WD AND PFO9 4WD THROTTLE SWITCH.

DAVE R