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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.'"
i can bridge 2 pins on the ecu plug on mine, and its flashes the dash lights in sequence to give me the codes, its just a matter of looking them up. though im not sure if newer cars are still keeping anything like this available.
Also, generally if your engine light comes on, your car will go into limp home mode, which is a cut back operation that uses default configs and ignores either all or some of the sensors just to enable you to get home, or to a workshop somewhere without the working sensors.
this is not my signature
CAN is a wiring spec and a protocol and falls under OBD-II; You can read all about the SNAFU on Wikipedia but the short form is that there are five protocols including CAN, which is mandatory on 2008 and later vehicles. Wikipedia doesn't make it clear that CAN has been allowed for in OBD-II for years, if not all along, but that is indeed the case. AFAIK CAN is the most expensive of the protocols to implement, so some OBD-II interfaces don't include CAN support. CAN is also commonly used for communications between the PCM and the computer which operates the transmission, so your PCM might actually have multiple CAN interfaces, though only one of them pins out to the OBD-II connector.
"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.'"
Washington was against political parties, and said so in his Farwell Address:
In contemplating the causes which may disturb our Union, it occurs as matter of serious concern that any ground should have been furnished for characterizing parties by geographical discriminations, Northern and Southern, Atlantic and Western; whence designing men may endeavor to excite a belief that there is a real difference of local interests and views. One of the expedients of party to acquire influence within particular districts is to misrepresent the opinions and aims of other districts. You cannot shield yourselves too much against the jealousies and heartburnings which spring from these misrepresentations; they tend to render alien to each other those who ought to be bound together by fraternal affection.
. . .
However combinations or associations of the above description may now and then answer popular ends, they are likely, in the course of time and things, to become potent engines, by which cunning, ambitious, and unprincipled men will be enabled to subvert the power of the people and to usurp for themselves the reins of government, destroying afterwards the very engines which have lifted them to unjust dominion.
But not everyone agreed, even back then. Washington was the first and last President to not belong to a major political party (except, kinda, John Tyler, who was thrown out of the Whig party).
Not a typewriter
If the mix is rich, and the computer KNOWS that the mix is rich, that narrows it down quite a bit. Then the only possibilities are the airflow sensor, or possibly the fuel pressure regulator. (Of course, if it's a car without an airflow sensor, it could potentially be the throttle position sensor or maybe the manifold air pressure sensor. But most cars rely on a MAF sensor nowdays.)
If the mix is rich, and the computer claims "fuel mixture lean" or believes nothing at all is wrong, the problem is most likely the O2 sensor, and the computer is being fooled into enriching the mix.
I think the codes are quite useful. They let you know what the car is thinking.
Legalize recreational marijuana. Seriously.