[Bill_B]

Anthony, that part is one of the electrical connection devices for the festo valves. If you don't have it clipped in correctly, the solenoid current will not reach the coil you want. It is perhaps why you are seeing the yellow color, although I do not recall ever seeing that indicator LED in the connector show yellow.

As to adequate voltage for these solenoids. There are white markings, smallish, on the side of each of the coils at the ends of the device. A rough guide (not definitive) is that if your solenoid came in a KoP tote box, or from FIRST Choice, it is probably 24v. If you bought it from Andymark, it is probably 12V. If you bought it anywhere else, look at the last three characters of the festo part number. If 1P3 it is 24V or 5P3 for the 12v version. Anything else there is mysterious and probably you cannot power it from your controls board.