Below was taken from the RAVE. I thought the IACV was normally closed, but it appears that the ECM opens the IACV at engine shutdown. So if you install a new IACV, you should be able to(theoretically) open the IACV by:
1. unplugging the IAVC
2. turning on the power(without starting the engine)
3. plugging in the IACV
4. Turning off the power
5. repeat until you feel the IACV is fully open.

Main relay

The main relay supplies the power feed to the ECM
with a tap off to feed the fuel injectors (8 amps) and
air flow sensor (4 amps). This relay is controlled by
the engine management ECM. This enables the ECM
to remain powered up after ignition is switched off.
During this ’ECM power down routine’ the ECM
records all temperature readings and powers the
stepper motor to the fully open position. Failure of this
relay will result in the engine management ECM not
being switched on resulting in engine not starting due
to absence of fuel and ignition.

 

Your theory is correct. IF a few factors exist like good connections and output signal from ECM.

 

may I ask which relay that is , I washed my 97 disco today then it would not start. I found a clump of hanging relays some yellow one green then a black one with heavier connectors on it ,it was full of water and quite corroded inside .thanks

 

It's the big black one beside the charcoal canister in the engine bay.

I just got hold of my new IACV and it came with instructions, it's an aftermarket Car Quest part. The instructions given are not the same than those in RAVE. It says to adjust length of the plunger by hand if it exceeds 1 1/8" or damage may occur. Once installed it is possible that the idle speed is abnormally high 1500-2000 RPM. You can reset your IACV and ECM by driving at 40 mph.

With the RAVE procedure I assume you do it before installing the replacement part so you can see it open. I also assume all the cars using the same IACV have the same housing length.

 

Man, I wonder if this info would have saved me a $100 trip to the stealer to reset the adaptive memory. Which took all of 15mins.

Maybe I should read the manual once in a while

 

I think
It's very different with the advanced evap