(I don’t speak German, sorry… I was going to use Google Translate but I thought that would be a huge mess, so hopefully someone can translate the general points)
I have done a lot of research into this, and I currently have a heated steering wheel on order to transplant into my 2020 M3P. I don’t expect it (heating) will work, but I expect it will be „heating capable“, if Tesla allows me to have the option coded.
The main points that have been confirmed by multiple sources are as follows:
Both the heated and non-heated wheel have the same design. Just because a wheel has metal scroll wheels and no seam at the top, it does not mean it has heating. Both 1095222-90-O (M3 - SW ASSY, PUR) and 1490214-CN-B (M3Y - HEAT SW ASSY, PUR MadeInChina) look identical from the outside.
There was at least a hardware change to the harness that goes inside of the heated-enabled steering wheel. An extra blue connector was added, which connects to the BOTTOM of the wheel - see bottom image on here: https://teslamotorsclub.com/tmc/posts/5445247/. Previous thoughts were that it was the blue connector on the right of the wheel, but this is wrong… it is the female blue connector at the bottom that plugs into a male black connector.
If you are curious you can take off the airbag and you should be able to see if this blue connector is present, without disconnecting the airbag itself.
If you have the blue connector - your steering wheel has heated steering wheel capability, but not activated. There have been a number of MIC LRs delivered in the UK that have not had features like front foglights or heated steering wheel enabled, and Tesla have pushed the features to the car.
More proof of extra connector on new vs old harness - https://teslamotorsclub.com/tmc/posts/5394043/
There is also a hardware change to the steering wheel controller in the bottom of the steering wheel. Unfortunately I can’t post a link to the Reddit post where this was found (max 2 links for new users)
MIC SR+s are all being delivered WITHOUT heating enabled, but they almost certainly have the same hardware. This points to Tesla offering it as an OTA upgrade like rear heated seat.
The good news:
All of the required hardware is in the wheel itself. If you buy a heated steering wheel (1490214-CN-B) it will have the new harness and controller already in the wheel.
In terms of connections and wires, it has been confirmed that the yellow and brown connectors that plug into the clockspring are the same. Therefore a MIC heated steering wheel could physically be installed on an older car, and the steering wheel controls, horn, etc would work.
The bad news:
After speaking to Tesla GB I was told that the prices for the non-heated steering wheel (1095222-90-O) is £475 inc VAT and the heated steering wheel (1490214-CN-B) is £975 inc VAT. Is steering wheel heating worth that much to you?
Even after you fit the wheel the heating won’t work because the option has to be coded to the car (see above about MIC LRs landing with front foglights and heated steering missing). Tesla have already enabled it on MIC LRs where it was missing, so they have the capability to do it. But whether you could get them to enable it on a car that should never have had it? That might be difficult.
I hope this has helped