Green one on the back of the head is the water temp for the ecu, yes you will need this one. And no, the one at the front of the head is the cluster water gauge, has nothing to do with the ecu.
Brown one is the thermotime switch for the coldstart. Which wouldnt be needed if coldstart isnt plugged in.
Yes yellow 2 plug on inlet is for the airtemp, not that it reads right anyways, only reads heatsoak.
Cheers
Steve
