Originally Posted by tabetha

Thanks ford!!
The thickness of that black/red would suggest to me it may be main relay/ecu power feeds.
Brown with no stripe is always earth(ground) on Fords, black is always a switched live.
The thin black looks like switched live from ignition.
Thin green is going to be tacho, join to ecu green.
Thin brown/white is temp sender gauge, look on sender to verify.
I would double check everything with a test light(not digi metre), does indeed look like they've been playing pick and mix there with colours.
With the brown/white I would do all the other wires first, then put a GROUND down this wire, one of two things will happen, either the temp gauge will go up, OR the oil pressure warning light will come on.
On a lot of fords the oil pressure warning light and the temp gauge sender are both brown and white!!, but oil pressure onnsome can also be brown/green.
Just work through it methodically, using a test light, and ignition to determine what is what, the ecu gets it's earth from the earth terminals where it bolts on the plenum cover, but when done run a seperate earth wire(only needs to be thin) to the ground bolt on the plenum where the engine/ecu loom bolts and back straight to the battery.
tabetha