If you live in the US- There is now an initiative push for Illegal To Repair-

[Mr Simpleton]

http://www.infoworld.com/article/2914003/government/dmca-copyright-law-could-make-it-illegal-to-repair-your-car.html

Sigh!

[jlmoon]

From that article:
"Manufacturers like John Deere use DMCA to maintain tight control over diagnostic tools needed to repair modern tractors. Farmers previously accustomed to DIY repairs now face a costly and time-consuming nightmare that requires flying in manufacturer-approved technicians to repair their tractors' very proprietary computer systems."
 

I have one of those Big New Greeeeen Tractors and had to pay out through the nose to have some diagnostics the only "John Deere" could do.

[Kjelt]

Guess the carmakers are breaking the way
http://wqad.com/2015/04/22/automakers-push-for-law-making-home-repairs-illegal/
And then it is only a matter of time, when other producers realise how much more money there is to be had.... 

I guess this is more a security matter. I visited the Embedded World Conference in 2013 and there was a security talk that was specifically about what could go wrong if you install car maker untested "accessoiries" to your Car's CAN bus.

The case talked about was a german car which had problems with its power steering esp. on the highway. It would have dangerous steering actions. It was brought to the dealer and they find out what happened. Now how power steering works in that particular car is that the power steering electronics listen to the CAN bus for the speed messages and the higher the speed the lower the extra steering power. So the slower you drive the more power is added to the steering power.
What this owner did was he had this multimedia system in his car that had a tv and dvd player that only could be operated when the car was stopped. So when driving this was disabled. He let a moonlighter install a gadget that allowed him to watch dvds while driving.
What this gadget did was isolating the CAN bus to the mediacenter and translating all the broadcasted CAN speed messages to a 0km/hour CAN speed message, and thus the media center will operate.
What the moonlighter did not realise is that from a certain year on the same branch of the CAN bus he isolated was also used for the power steering electronics futher on that branch.
So the power steering would also always get the 0 km/hour messages and thus give full power to the power steering.
This was not a big problem in the city but driving 160 km/hour on the highway even a slight change in steering would be overly powered making it a very dangerous vehicle.

So I don't blame car manufacturers for trying to prevent this kind of misconduct, but what they should do is make the CAN bus security better by encrypting/signing all the CAN messages so only the manufacturers electronics can decode them and sent them in the first place.

[smjcuk]

The car manufacturers forget what stupid cock ups they make so they're in no position to start making demands.

My father has a range rover. When you turn the head lights on, the navigation reboots. When you plug an iPhone into the USB socket in the dash, the headlights don't work. Dealer three times, diagnostics, can't reproduce. Plus the thing thinks he's cpaped the EGR valves but they aren't so it has adjusted engine parameters so it knocks when it runs.

Also if they're going to be honest, CAN is a network so they should be providing two bus implementations in the car: one critical bus for all functions that are safety critical. Hell they shouldn't even use a bus topology, it should be a point to point network. Then a DMZ network for all ancillary functions that the user can extend i.e. for phone handsets, media systems etc.

As for bus encryption, this should not be allowed. Absolutely no way at all. Otherwise it's not your car.

As for safety, all critical systems such as power steering, braking and engine control should be totally isolated and operate independently, preferably with hardware control backup (PS pumps disengage, hydraulic brakes only, engine and box fails to disengaged) rather than what the hell lets go batshit mode.

This makes me want my 1974 Land Rover Series III back. I burned ALL the electrics out in that after a short, went meh, crank started it and drove home.

[free_electron]

What the moonlighter did not realise is that from a certain year on the same branch of the CAN bus he isolated was also used for the power steering electronics futher on that branch.

So I don't blame car manufacturers for trying to prevent this kind of misconduct

I BLAME the car maker. What moron puts safety critical information on the same bus as the entertainment messages ?
That should be isolated. Bunch of lazy oafs running everything in the same bus... Just get a CPU with more than one CAN engine and split the damn things.

Better even : use Flexray for the mission critical stuff.