I am using the OEM IACV that came off the Zetec; Mine is then mounted back on the plenum via a bracket I constructed (IACV Mount, IACV Plenum)
I spent a long time trying to research the wiring for this thing, its a PWM coil based valve, 'some' forums mention 'some' valves need a flyback diode to prevent damage, essentially protecting the circuit and valve solenoid from reverse current when the power is turned off during its operating cycle.
Checking the Ford IACV it seemed to have the same resistance in both directions - which my basic electronics told me it doesn't have an internal diode and possibly no poliarity preference. More searching on the web turned up some pictures of the plug and wiring - I decided to go with the one that matched the socket I have & include a flyback diode thus:
I'm taking the 12v switched feed from the Aux panel connector - grey cable - to my black cable
The ECU switch from Pin 3 is my blue cable
Update Changed the 12v feed so it doesn't run from the Aux panel & Aux fuse - otherwise I'd lose IACV and tickover if the Aux fuse blows
I'm taking the 12v switched feed from the Aux panel connector - grey cable - to my black cable
The ECU switch from Pin 3 is my blue cable
Update Changed the 12v feed so it doesn't run from the Aux panel & Aux fuse - otherwise I'd lose IACV and tickover if the Aux fuse blows
Emeralds manual page shows connection of a switched 12v to one side & the other returning to pin 3 on the ECU (Note in setup later - the frequency needs to be 300hz not the default 120 pictured on this manual page)
ECU socket diagram to help work out the additional wires; I'm using pin 3 for the IACV control and pin 35 for the map switch. Emerald supplied me with half a dozen extra pins and moisture gromets for their plug; so this was a case of crimping on a couple of wires and carefully pushing them into the ECU plug from behind. The plug doesn't need any dismantling; the pins push in then 'click' permanently into place:
I still wasn't sure of my wiring, so for now I have the relevant loom leads trailing across the car and wired to the IACV cables & flyback diode with a chock-block. This will all be tidied up when I am sure I have the circuit correct:
