92 4.3 temp sender for gauge error

One day I noticed the temp on the dash was showing totally cold, even tho the engine was warn and the heater blowing hot air! My 92 s10 blazer with the 4.3 Vortec CPI had an issue. I checked the sender for the gauge and when I pulled the connector off the whole end had rotted off the sender. I put in a new sender and now when the ecm (or whatever its called) times in the temp climbs up slowly till its pegged out and the check gauges light comes on the dash. It measures about 3K ohms ambient. So I went to a dealer thinking aftermarket was off some.... measured the dealer item and it was the same. I guess too low resistance measures hot all the time. That did not help. I put a 10K ohm variable resistor in place of the sender and was able to set the gauge reading wherever I wanted so it seems that the circuit is working. I wanted to install the variable resistor under the dash instead of under the hood but am unable to find the green wire on the ecm connector. Can't seem to locate a wiring diagram of the sender so unless someone has one handy I'll be mounting it under the hood!