3.9 wiring

Ok, not my field of expertise, but there’s info in the workshop manual for the later NAS spec D1 with the later GEMS engine i believe, the filter canister is different but the principal may or not be the same, I quickly flicked through the pages thinking that not applicable for my disco.

Hi guys I’m running a rear mounted rad , is it a good idea to blank this of or do I need to run it somewhere

Just joined the site so not a good start to hijack another thread but thought some of you experts may know the answer.
The input lead that plugs into the IAC Valve (on a 3.9 V8 from a 93 Disco). Should all 4 pins be live all the time? Put a light tester on them today, 2 give a response but 2 don't. Would this change as the engine warms?
One of many theories for my high idle issue I've got at the moment.