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Thread: RETROFIT MEMORY SEATS PASSAT B8

  1. #11
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    ^^^sam: Hi. In the absence of anyone else with greater expertise responding - yes, ASAIK your greatly truncated synopsis of how the CAN bus operates is not incorrect. I would guess that within limits and so long as the impedance loading on the CAN high/low wires isn't a problem - splicing into the wire-pair at any point is OK.

    Don
    VW Golf MkVII (MY13) - A3 8V hatch (MY17)

  2. #12
    Verified VCDS User sam1754's Avatar
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    Yes indeed, I just wrote what I've understood. A few months ago, I used VCDS like a dark tool which make me solve problems... I prefer learn more now. If someone know where I can learn more about VAG CAN Bus, I would read it with pleasure.

    Thanks Don

  3. #13
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    Sam: Given the clear elevation in your understanding over such a short period of time, I have absolutely no doubt that you have the intellectual capacity to learn quickly!!

    Purely as a suggestion towards furthering your knowledge - perhaps read SSP_186 as an introduction. Then, if your intellectual appetite is sufficiently whetted - proceed to read SSP_238 followed by SSP_269

    Don

    PS: apology for providing links to the English version of SSPs - I suspect if you search the net, you could probably find French versions
    VW Golf MkVII (MY13) - A3 8V hatch (MY17)

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  5. #14
    Verified VCDS User sam1754's Avatar
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    Great!
    It would have taken me a long time to select these really interesting documents on the web.
    I'm very grateful!

  6. #15
    Verified VCDS User sam1754's Avatar
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    Hello, I read the documents and learned more on CAN BUS communication. It's really interesting and it made me understand strange things that can happen in the car.

    1. According to the priority messaging system, when a problem occurs (not serious but triggers the engine alert), we have an engine alert on the dashboard and just after a second related alert from another controller. Not really important, but it is better to know why it is done this way.

    2. Along the coding of the controllers, I saw that certain parts or sensors which were actually implemented on the car were recorded as "not mounted" or "not installed, not coded" on certain modules. Depending on the vehicle's equipment, the elements are connected directly to the controllers or to the onboard network BUS. Sometimes, the sensor is used for several units but when it's used for only one unit, there's no reason to make it communicate with all modules. So, VW made sub-networks or direct connections. Some modules'firmwares allows the two options which can be coded. In the Passat, it's the case for rain sensor and many others. I.e., we only select communication mode with those components. If it's coded on the module, identification and priority module's code is recognized on the bus can and data can be shared.

    I know now why wires are interlaced (to avoid magnetic perturbations) + the two wire doesn't have the same working voltage but signal shapes are similar or opposite to limit inducted magnetic fields.

    But in my car, near coupling points wires aren't interlaced on several centimeters (factory fitting) and there's no trouble... Is this allowed by self error control through comparing the two wires signal???

    Beside this, I read other SSP on Passat and diagrams to find the best way to connect driver seat controller. It's on harness just before door's coupling point on confort CAN Bus. It seems to be easy and nearly conform to factory fitting diagram.

    I didn't find anything about the best way to connect CAN wires to other ones.

    Thanks for all informations, comments or documentation :
    Last edited by sam1754; 01-21-2020 at 04:35 PM.

  7. #16
    Benevolent Dictator Uwe's Avatar
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    Quote Originally Posted by sam1754 View Post
    But in my car, near coupling points wires aren't interlaced on several centimeters (factory fitting) and there's no trouble... Is this allowed by self error control through comparing the two wires signal???
    CAN bus wiring is more forgiving than you might think. I mean, it's only 500 kbps....

    Quote Originally Posted by sam1754 View Post
    I didn't find anything about the best way to connect CAN wires to other ones.
    Provided you connect it correctly (don't reverse polarity) and you use twisted pairs, it's not all that critical.

    -Uwe-
    The engineering problems are likely insurmountable. It would be like proposing to land a rocket booster section on a barge floating in the middle of the ocean.

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  9. #17
    Verified VCDS User sam1754's Avatar
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    Quote Originally Posted by Uwe View Post
    CAN bus wiring is more forgiving than you might think. I mean, it's only 500 kbps....-Uwe-
    Wow, it's very fast! It's my internet connection speed!!!

    Oups, I lost some data on a crash:
    Last edited by sam1754; 01-22-2020 at 06:23 AM.

  10. #18
    Benevolent Dictator Uwe's Avatar
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    Quote Originally Posted by sam1754 View Post
    Wow, it's very fast! It's my internet connection speed!!!
    If so, chances that's a several (5 or more?) km long DSL connection -- coming in on Plain Old Telephone wires that aren't even a twisted pair.

    -Uwe-
    The engineering problems are likely insurmountable. It would be like proposing to land a rocket booster section on a barge floating in the middle of the ocean.

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  12. #19
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    Yes indeed!

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  14. #20
    Verified VCDS User sam1754's Avatar
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    Let's go!





    I recieved interior from a 2014 SW demonstration car in great condition like new. But I understand now that we musn't pull back airbag unit without disassembling backrest!
    I had to dismantle all the seat to put back all brackets linking leather cover to foam piece.

    It's not unuseful, we always learn...

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