Where to hook up electric temp gauge?

[kpc_0721]

Ok so I could never figure out why my tach and stock temp gauge were never working until a couple weeks ago so I bought a autometer electric water temp gauge. There are to sensors on the front of the intake manifold and I cut into the one on the left where the actual sensor is hooked up and it worked perfectly fine. I was going to put my glovebox back on because I had taked it off to see if I could pull the heater core from there but anyways when I was down there I noticed that I had a big green plug that looked like it was coming out by the ecu so I plugged that in and my tach and stock temp gauge started working or so I thought....after I plugged that in my stock gauge went up about halfway right away and my aftermarket gauge shot all the way past max like they are interfering with eachother?!? Does anyone know what would be causing the gauges to do this? And also when the big green plug is not plugged in my aftermarket temp gauge works fine but my tach and stock temp gauge dont work at all. Sorry for such a long post but thought u guys needed to konw all the details....Any help at all would be greatly appreciated and also does anyone know what that big green plug is???

[nissanfanatic]

The scaling is probably exactly backwards from the autometer probe and stock probe. Use the autometer probe with your autometer gauge. Buy the Greddy coolant adapter and you can use the autometer probe I believe. Check to see if it is 1/8" NPT threaded first.