Outer Limits 4x4 Board

as the above describes i need some help hooking up the oil pressure sensor. I have a td42 GQ and i replaced the speedo cluster with one that has more guages, one being the oil pressure guage. I got hold of another (bigger looking?) sender which i thought was the one for the guage and im just not sure where to hook up the spare wire?? The original one i had on my car only had one wire going into the loom, this one has two wires? i just guessed that one wire was for the light and one was for the guage. i have connected one wire to where the other wire came from and the light that was staying on turned off so im assuming that part is fine, i just need to know where to join this other wire?????

any help would be appreciated.

Cheers

TinyGQ