1999 GMC Sierra

I have found out the heated automatic side mirrors I put on replacing the non -heated automatic mirrors I took off, have 5 pins in the 8 hole connector. The old non - heated mirrors have the 3 pins in the 8 hole connector. The truck side of the connector has the 5 pins. In the same location as the heated replacement mirrors. Does this mean the heat will work in the mirrors when the defroster is turned on (as answered in a previous question)? Or is there a fuse that needs to be inserted or some other thing?