I watched a video yesterday, this guy had a Dodge Ram, 2009 to 2012 year model.
He removed the driver's seat, then separated the seat from the seat back.
He had purchased a High/Low seat heating element pad, that he slipped right over the OEM heating pad.
The new unit had a switch & 4 wires, he did not touch 2 of the OEM wires because one of those wires was for the Air Bag & the other was for the cooling part, which also has a safety circuit, that shuts everything down, in case of over heating.
The other 2 wires, he hooked up to the OEM switch, using solder & heat shrink.
The strange part was that the part of the seat upholstery that your butt slides over, i think it is called the Bolster was completely shot & should have been replaced !!
It would have made the installation of the seat pad much easier.