WIFI OBD-II plug in for checking car and motorcycle error codes

boing
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I was looking around for an open source Linux solution to this after I blew the $20 on the thing but there is no open source database of the codes. All the stuff is proprietary. I was really naive when I bought it. I totally thought that I’d not only be able to get the error codes, but that I’d also be able to initiate an ABS brake bleeding procedure! I learned a lot real fast. Only the $1500 tool can do it, and even then maybe not. You might have to use the car manufacturer’s windows software to perform bleeding procedures depending on the make. And I didn’t even look into any of the other problems like oxygen sensing. I was only interested in brakes and came up short.

I did save myself a ton of cash though. Here’s what I did. The problem was a blown ABS pump. New for a Toyota, that thing is about $750 or more. But I bought one on eBay taking a gamble that it was ok. I bid and won for $100. It showed up in bubble wrap. The problem with replacing an ABS pimp is two fold. First, you have to carefully disconnect all the little brake fluid pipes connected to it. In a ten year old car this is a tricky task because if you damage one you are looking at an involved teardown to replace that metal line. So you gotta be careful & lucky . Second, once the new pump is in, you have to bleed the brakes. On an old VW, that’s easy you just pump the brakes and feed the master cylinder fluid until all the air is out. But on newer cars with ABS, you can’t do that. You gave to cycle all the valves in the ABS pump in sequence. You need the computer to cycle these valves.

So I took the pump and a printed copy of the Toyota shop manual on ABS bleeding procedure to the mechanic down the street. I also put a ton of Kroil on all the little ABS pipe connections. And I got an old toothbrush and cleaned them really well and put more Kroil on them. Then I spoke to two mechanics, plead my case to install this part and not hold them responsible if it didn’t work. We agreed that they would douse the connections with more Kroil and leave it sit over the weekend before trying to disconnect it. Then they’d replace the pump and use their computer to do the bleed.

Long story short, it worked great. Total repair: $300. Expected repair cost: $1500. Saved myself at least a thousand bucks by doing all the legwork and parts acquisition.

I don’t know why I typed all of that. Bored I guess and proud of myself for solving an annoying problem despite being so ignorant about cheap code readers.

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The missing code list IS a major problem. Can we crowdsource them from various leaks, acquire/hack/steal/pirate software and reverse-engineer the magic numbers out, dump the firmware from the car chips and get the numbers, or any combination of the above?

As of cycling the valves in sequence… would it help to disconnect the valves from the controller unit and manually activate them one by one? The computer is issuing signals, opening power transistors that actuate the valves. Replace the transistors with pushbuttons for a test/bleed rig (or just touch wires)?

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I considered that. But what I didn’t want to get into was having my car disabled in my driveway. Doing that properly would have been done best by not going in blind and actually seeing a few different brake bleed procedures and try to capture what they do. Reverse engineering one seemed like folly.

I do like your idea of gathering the codes and keeping them in a big open source db. The car industry isn’t geared towards consumer do it yourself ism. It’s totally a racket for the manufacturers and big oil. An open source car would be the shizz. I would totally buy one.

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I got another thought how to get air out. Open all the valves, attach a vacuum pump and suck the air out, then let the air pressure (about 1 kg/cm2) push in a new fill? (Assuming the parts can handle the external air pressure. The alternative is filling with oil, THEN attaching vacuum and letting the bubbles out, while minimizing the hydrostatic pressure of the oil by positioning the system.)

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The usual recommendation is “buy Torque for your phone” - it’s something very reasonable like $5.

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Unfortunately, the world is a cold, horrible, place where Standards proliferate and ‘meaning’ is a cruel illusion.

Somewhere between 1994 and 1996 you actually get (usually) an OBD-II connector and some semblance of standardization. Earlier things that are conceptually similar exist; but do absolutely whatever they want, over whatever protocol they want, on whatever pinout they want.

If you do have OBD-II, five exciting protocols are available, which one, or ones, you get depending on your vehicle(CAN did not meet regulatory requirements for OBD-II before 2003, though a vehicle might have it along with one of the others, between 2003 and 2008 it did meet requirements; but was optional, after 2008 it was required).

Then, at least for the ‘serial’(either actual serial port connected, or bluetooth/USB-acting-like-a-serial-link) units, not sure about this wifi stuff, you typically have either an ELM327, STN1110, or cheap, cheerful, possibly horribly broken, chinese clone of one of those, OBD-II translator chip doing the talking on the OBD side, while (ab)using another extension of the ever-flexible ‘very much like Hayes AT’ family of command sets. Assuming you do have a CAN bus, exactly how unmediated your communication with it is depends on how eccentric the chip doing the translation is. In theory, you should be able to do anything, it’s either a 250 or 500 kBit/s CAN bus, and USB UARTs tend to be good for a few mB/s, so it’s not a firehose-through-a-straw data sampling problem; but the ELM327 or colleague isn’t just handling level conversion and may or may not be quirky.

Once those joys are attended to, you run into the problem that only emissions-standards related data are actually a regulatory requirement. Anything else, following SAE J1979 is considered polite; but optional, and non-standard PIDs are wildly common, with access to them being pretty patchy and dysfunctional(also expensive).

Plus, if it is a CAN bus, OBD-II PID query is one type of traffic that can occur; but nothing forbids the use of the CAN bus for whatever non-OBD traffic, following whatever conventions, the manufacturer wishes. Access to this information is unlikely to be any easier or more polite than access to nonstandard OBD PIDs.

In hardware terms, I wouldn’t necessarily trust your basic $15 fleabay special to actually provide transparent access to the CAN bus, at least not without a few nasty gotchas; but the world is rotten with relatively cheap microcontrollers and SoCs that have CAN support as well as other interfaces, so getting transparent access should be within talented-DIY reach, and likely under $100 in modest quantities, obviously less in larger quantities.

Prying loose the details of what exactly is being talked about on the bus, though, could be a fairly epic affair.

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Just like with regular old school bleeding, it has to be done one wheel at a time because the lines are different lengths and you have to isolate the pressure into each one to push the bubbles out. Imagine trying to fill four jugs with one funnel simultaneously. You’d either never get all the air out or you’d waste a ton of your filling liquid.

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For the motorcycle Tune TTP is the software package, I think. More intended to let you tweak fuel injection settings you can also turn off sensors and warning lights, I believe.

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You can use a Linux computer with SocketCAN drivers and a compatible hardware interface (some shown here.

Then you can use e.g. Wireshark to monitor/analyze the communication.

Reverse-engineering the payloads is however a separate 55-gallon barrel of worms…

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Interesting… Apparently the Beaglebone Black can be coaxed into exposing its CAN interface(possibly even two of them) and TI SoCs are among the CAN intefaces supported.

I think you may have just found a good project to keep mine from getting fat and lazy on my desk…

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Yeah, that’s cool. You’ll like this thread and what it contains that you can download:

http://www.mp3car.com/software-and-software-development/128438-update-obdii-manufacturer-database-version-2-0-now-touch-friendly.html

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