I just got my hands on a heated steering wheel. It has a four pin connector with two red wire and two black wires with a stripe. Oddly enough, there is no continuity between the red wires and the black wires. The continuity is between the two red wires. I think there is about 2.9 ohms of resistance. Connecting a 18v power source to the two red lines caused the steering wheel to warm up. If you trace the black wires, they go to two VERY think gauge black wires, but I am not sure what they do.
I had planned on simply running wires to a 12v source with a physical switch to control the heat.
I removed the airbag and controls from my current steering wheel, and the problem is that there is no space to run additional wires through the steering column.
There is are two connectors on the steering column, which a yellow one that connects to the airbag and a brown one that presumably are for the steering wheel buttons. The airbag connector is a 6 pin connector that uses only 4 pins. The brown connector is also a 6 pin connector with only 4 pins. The sockets for the connectors in the steering column have four blades for the yellow airbag connector, and 5 pins for the brown control connector.
I am thinking i would rather NOT run the heating power wires next to the airbag connector, so I am thinking to run the power line through the socket for the brown control connector. Clearly there is power that runs through this connector, but I doubt the wires could handle the current for the steering wheel heater. A youtube video indicates that the steering wheel heater uses about 95 watts, which is about 8 amps.
I have examined photos of the steering column "clocks" from the newer and older model S, which show that the newer columns have two extra pins in the bottom, (which could support the heated steering wheel function. But my understanding is that to use the new column, you may have to reprogram the car to recognize my steering wheel buttons.
(as per a post here:
Hey guys. I just pulled this off. You need to have the firmware reprogrammed for the car to recognize the new steering wheel switches. Reprogramming is a pretty simple fix if you have the ability to reconfigure your car with someone that has some skills with computers or access to Tesla toolbox. The problem is that the old configuration is expecting a LIN wire input, however with the newer setup up, it is all CAN bus. So the switches are sending signals, but there is nothing on the bus that is programmed to hear it.)
So far, I have only spent about $350 for steering wheel... hopefully someone wants my old steering wheel which is in great condition!