Howdy,
tried measuring resistance across the three wires from the tps.
I got reading of around 2 - 4K across more than one pair of wires and am confused now.
Does anyone have the wiring written down or can help me with what to look for while testing the tps?

The Haltech has three wires, earth, +12vdc, and signal which i need to connect to the tps.
Cheers,
Billy.

Of the three wires on the tps, two should have a constant resistance regardless of throttle position. These are the connections for the 12V and the GRND. The other wire should change resistance as the throttle moves, this is for the siganl wire. Do the connections then check that the output on the signal wire is a low voltage at idle, and a high voltage at full throttle, if it's opposite, then swap the 12V and gnd over.

PS, you must use a variable type TPS, a simple switch type will not work properly. I would assume that the old XF falcons were switch type. (ie, either on or off)

my xf tps measures 8k across the orange and black cables,
green cable is the signal wire...

hey mate if is the standed xf tps it wont work on the haltech i had 2 get another tps i got mine from haltech.