4 ms·

That would require an authentication chip on the heater side, which considering the price of USB-C cables / Apple accessories, and the ultimate goal for the car

That would require an authentication chip on the heater side, which considering the price of USB-C cables / Apple accessories, and the ultimate goal for the car makers is to save money / make more money, does not make much sense. That said, fault detection is very common on modern car electronics, especially safety-critical components. Your throttle-by-wire pedal has 2 redundant channels that output 20% to 80% signal, possibly mutually complement or some other scheme. Your airbags have open-/short-circuit detection. However these are never actively designed to defeat circumvention, so you see after-market steering wheel makers supply you with dummy resistors that pretend they are airbags. EDIT: I could imagine the entire seat or steering-wheel assembly sharing one microcontroller which has encrypted communication to the vehicle's "Body Controller". That would defeat wholesale replacement / MITM, but still does not prevent you from co-opting the physical connection to the actual heater element. You would most definitely break (e.g. bumper-to-bumper) warranty but who cares.

lukevp 6y ago
I owned a 2003 bmw and there were many modules within it (for example, the rear trunk latch was its own module). With CAN bus electronics it’s super cheap and they design a lot of the parts to operate this way, and they don’t directly interface with the ECU. They could have a relay in the ECU that provides the power output to the heater wires and it will only operate if the CAN command has a signed payload that uses some key from BMW, and compromising that key or sharing it would be in violation of the DMCA, similar to the Sony PS3 key that happened many years back [0] or the current battleground of right to repair John Deere tractors. That would make it not technically impossible to create another replacement part, but it would violate copyright. [0]: https://en.m.wikipedia.org/wiki/PlayStation_3_homebrew#Private_key_compromised https://en.m.wikipedia.org/wiki/PlayStation_3_homebrew#Priva...
- smilekzs 6y ago
  If there is a relay then you can simply ground a leg of it and get power. Or you could add-a-fuse and provide power. As long as the heater itself has wires going between the seat and the ECU / relay box then you have a way. I doubt the manufacturers would go this far, but it is entirely possible for the relay / power electronics to be an integral part of e.g. the seat control module, then you'll have a hard time.

lukevp 6y ago

I owned a 2003 bmw and there were many modules within it (for example, the rear trunk latch was its own module). With CAN bus electronics it’s super cheap and they design a lot of the parts to operate this way, and they don’t directly interface with the ECU. They could have a relay in the ECU that provides the power output to the heater wires and it will only operate if the CAN command has a signed payload that uses some key from BMW, and compromising that key or sharing it would be in violation of the DMCA, similar to the Sony PS3 key that happened many years back [0] or the current battleground of right to repair John Deere tractors. That would make it not technically impossible to create another replacement part, but it would violate copyright. [0]: https://en.m.wikipedia.org/wiki/PlayStation_3_homebrew#Private_key_compromised https://en.m.wikipedia.org/wiki/PlayStation_3_homebrew#Priva...

smilekzs 6y ago
If there is a relay then you can simply ground a leg of it and get power. Or you could add-a-fuse and provide power. As long as the heater itself has wires going between the seat and the ECU / relay box then you have a way. I doubt the manufacturers would go this far, but it is entirely possible for the relay / power electronics to be an integral part of e.g. the seat control module, then you'll have a hard time.