First:
Which bank is which on a NA Discovery 2, I believe its Drivers side is bank 1 and passenger bank 2

Second:
When I go to start the truck and have the key in the on position but engine off the IACV humms quite loudly, is this correct. I swapped it with another one I had and it does the same.

Thanks

 

You are correct on the banks, they can also be referred to as bank A or B, A being the drivers side.
Do you have a service engine light on, if so get the code numbers and get back to us.

 

Thanks Mike
No engine lights at all and pulled no codes. I have 2 o2 sensors (bank A #1 & bank B #1) reading 0.0v and still no engine light or codes and this has me really baffled.

 

Oh, and if I unplug (while engine running) the o2 sensor which I tried on bank b #1 the reading goes to 0.4v and no light still.

 

Reading 0.0 volts on the OBDII connected scanner? Or with your volt meter?

 

OBD2 scanner