Slashdot Mirror
Right-to-Repair Law To Get DRM Out of Your Car
eldavojohn writes "Ralph Nader's back to hounding the automotive industry ... but it's not about safety this time, it's about the pesky DRM in your car. Most cars have a UART in them that allows you to read off diagnostic codes and information about what may be wrong with the vehicle so you can repair it. Late model cars have been getting increasingly complex and dependent on computers which has caused them, as with most things digital, to move towards a proprietary DRM for these tools, diagnostic codes and updated repair information. This has kept independent auto-shops out of the market for fixing your car and relegating you to depend on pricier dealers to get your automotive ailments cured. The bill still has a provision to protect trade secrets but is a step forward to open up the codes and tools necessary to keep your car running."
The real problem right now is reprogramming data. OBD-II cars (everything 1996+ and some earlier) have standard protocol, connector, pinouts (kind of), et cetera. They also have standardized codes. But there are also manufacturer-specific codes which are only required to be provided for a reasonable fee which means (in practice) they can be presented as a book of text and they can charge you a hundred bucks. And most importantly there are manufacturer-specific codes which get sent to the PCM ("powertrain control module", what we used to call the ECU or "engine control unit"... but PCM is standardized terminology per OBD-II spec) which are used for tuning, for example for altitude.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
Time to spend more of my state-sponsored education. The mandatory light on all 1996+ cars is known as the MIL or Malfunction Indicator Light. The MIL lights when your vehicle's emissions are out of spec for any reason. I shit you not, that light is there specifically to tell you that your car is putting out excessive emissions. This happens whenever any of the "monitors" fails. A monitor is a list of conditions. Most monitors are "trip" monitors; a trip is a certain set of driving conditions. For example, if you run the vehicle at 50% or more load for a certain period of time and then coast for a certain period of time the car will operate the EGR (exhaust gas recirculation) valve, and it then has a chance to test to see if it is working. There's also a comprehensive monitor which runs every so often (pretty often actually) and checks to see if any sensors are giving a value which seems exceptionally wacky, either on its own or compared to the state of other sensors.
The MIL will clear itself so long as the fault was not serious (IIRC there are four conditions) if the monitor which failed passes three times in succession. All this is from memory so, bear with me if I get something slightly wrong. When it happens a snapshot is also stored. This is some of that "black box" data that can tattle on you in an accident; the car knows the position of the accelerator pedal and how fast it thinks you were going (and usually also knows what gear you're in and how many RPMs you're making, anyway, from separate sensors/senders) as well as the state of every other sensor under the hood, and possibly some others. There may also be a CEL (check engine light) and if the manufacturer is feeling particularly benevolent, a "check gauges" (or even "check gages"... heh heh) light which lights if, say, your oil pressure is low or your coolant temperature is high, but not so high that the computer thinks that what the sender is saying can't possibly be right.
Anyway, when any major sensor/sender flails the car will go into limp-home mode. It will also happen if there are repeated misfires, but misfires cause at least one of the monitors to fail (I forget which one though, sorry) and should light the MIL. The limp-home mode will not only retard the timing and thus reduce performance and worsen emissions, but in some cases it will also restrict maximum speed. When limping home the vehicle usually runs rich, which can kill your catalytic converter but which helps reduce misfires due to many types of engine problem.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"