there are 3 coolant temp sensors on the engine - 2 on the end of the head below the distributor - one is for the temp gauge (green in the picture below) - it has a 1-wire connector with yellow/green stripe wire - one is for temp signal to the ECU (red in the picture below) - it has 2-wire connector with red/white stripe and green/white stripe wires - a problem with this sensor will cause a Check Engine Light with error code 6 - the 3rd sensor on the engine is for the cooling fan - on OBD0 engines, it is on the back of the block next to the oil filter (blue in picture below) and on OBD1 engines, it is on the thermostat housing - it has a 2-wire connector with black and yellow/green stripe wires
the white sensor in the picture is for the oil pressure