The 1G ECT connector is a Tyco connector, the OEM supplier. It is for the Engine Coolant Temp sensor. It is supplied with terminals to match.
There are 2 different terminals used in this. One terminal has a locking tab on it, and is used in the slot with the unlock tab on it. This
terminal is what locks the connector onto the sensor. This terminal will not properly fit into the other slot.
The other terminal is not locking.
DSM 1990: ECT
DSM 1991-1994: ECT