In TPC, there are only 3 body controllers/modules listed. Would need to locate and mine to verify whether they changed since my 2020 model year.
View attachment 739590
If the body modules are the same part number, then maybe it is a harness? Although the wiring all seems to line up...
It's actually VCLeft that handles it, I think, given the wheel is traditionally on the left hand side of the car. The EPC shows the body controllers as from looking from the front of the car, so the one shown visually on the right is the left controller, and vice versa.
I have bad news, however..
I have had a look into the body controller modules yesterday, and also spoke to Tesla again to find out which one my car has.
There are 4 revisions of this module on the EPC that I can see, for the Model 3 at least, and it appears likely any car built before late 2020 has the same module that mine does. Mine has
1078673-32-L (not verified by sight, but that's the part that comes up for my VIN). There is a
1078673-90-K which I'm guessing is for even earlier cars.
There is also a
1567455-00-C and
1567455-02-D. Even though the former says "M3 2020" I suspect this is for late 2020 cars onwards, with "GEN 3" being on very recent cars. I imagine from the part code that the two latest revisions are very similar if not the same electrically.
Not too bad so far, maybe just a replacement body controller needed. Unfortunately -
1078673-32-L and
1567455-00-C have completely different electrical connectors.
Here is a photo of the former, and
here is the latter. As you can see there are some similar connections, but several are completely different.
At the very minimum then I think this would require a replacement harness, possibly several given that the left body controller controls everything on one side of the car, and you'd possibly need to replace whatever parts are at the other end, as the new harnesses might have different connectors at the other end too. At that point you're basically potentially stripping one half of the car down. Also - this all assumes that the car would be fine with having a different revision of body controller & attached parts operating one half of the car.
So, yeah.. if the heated steering wheel "needs" a revised VCLeft body controller to work, then it also needs at least one revised harness, probably several, as well.
It's not looking good...