Asking for a friend, on her 2018 Sierra she took it in to the dealership to have the gel battery replaced. They didn't have the right one and they put in a loaner battery. Now the heated seats don't work. I haven't looked at it yet but if anybody has an idea I will go over and check it out. Her new battery will be in in another week and maybe the dealership can check it out . Thanks.

 

As with all electrical problems always check the fuses and relays first.

 

That will be my first order to check.