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We are using an OBD device (https://freematics.com/products/freematics-one-plus/) for some research work. We tested on several cars like Honda 2006, Subaru 2018, VW Golf 2013, Mercedes GLK 2017, etc. and it works fine.

Recently we had problems with 2 different Honda models - 2015 Accord and 2016 Civic.

The device is not able to connect to either of these. We see a booting event, but the OBD does not initialize.

Moreover, on the Accord, plugging in the adapter causes the Forward Collision Warning and Lane Departure Warning systems to fail -- it sets off the systems failed warning lights. (I can send photos).

We connected other adapters like Torque and another cheap Bluetooth one and they both worked fine.

Any ideas what could be happening? The OBD port (CAN bus) is set to auto detect the protocol which I think on the Honda is the 500kbps CAN.

  • Have you contacted Freematics about it? Seems like they should be able to tell you what the deal is on it. They also have a forum where you can ask questions about it. – Pᴀᴜʟsᴛᴇʀ2 Sep 8 '18 at 13:56
  • Yes, I did contact Freematics. It is possible that Honda may be using some of the non-CAN pins for proprietary use that may be causing the issue. We'll be doing some experiments soon, will post the results here after. – Abhay Ghatpande Sep 9 '18 at 0:16
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I would almost certainly say that it's a problem with the Freematics device rather than the Honda, even though manufactures are making it hard to analyse can bus messages through the OBD port they still have to respond to OBDII PIDs.

Looking at the wiring diagrams for both Honda models I can see that pins 6&14 are connected directly to the CAN Bus network rather than going through a gateway so I can't see any issues here.

The schematics of the Freematics device however show that there is a 120ohm resistor connected across the CAN lines this isn't needed as there will already be two modules the termination resistors. When plugging this device into the OBD port it will add resistance to the buss probably causing the warnings. The fact that this resistor has been added along with other issues with the schematics make me wonder about the quality and design of the device.

I would remove the R11 from the device and try again.

  • thank you! The schematics I have are here: freematics.com/dl/FreematicsONEplus_schematic.pdf Which one are you using? My schematic show R57 as 120 Ohm across CANH and CANL. Is that what we should try removing? Really really appreciate this level of digging a lot! If it works, I wouldn't know how to thank you! – Abhay Ghatpande Nov 8 '18 at 23:28
  • Yeah that’s the one on your device, remove R57 and see how it goes – Terry Gould Nov 9 '18 at 6:35
  • Terry Gould is there any way we could talk offline? Is there a way to reach you? Could you contact me on my first name dot last name at gmail. Thank you. – Abhay Ghatpande Apr 9 at 2:43

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