F800GS CANBUS Stebel Quandary

Discussion in 'Parallel Universe' started by Dieselboy, Sep 24, 2008.

  1. Dieselboy

    Dieselboy Journey not Destination

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    That is actually one of my suspicions. Unfortunately, work has been nuts and I have been unable to pursue this at all this week.

    The last thing I did was run a new ground wire to the AP1. I need to re-ground the Stebel and test a new connection to the AP1.

    You have to remove 13 screws in order to remove the top cover and left side cover. While that is not an overly large number, try doing that 2 or more times in a row (BTW you have to re-insert them too). It gets old quick and consumes time in a limited evening.

    Since I have the horn working (which I actually had to use on the way home last night-- car drifted onto the line next to me) I am less manic about solving the AP1 issue. I will get there.
    #61
  2. MJS

    MJS Long timer

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    The resistor wires across the relay coil terminals (in parallel). I removed my horn so the resistor was required to imitate the electrical load of the stock horn. The ZFE doesn't know what the load is, only the current draw. The resistor is close to the stock horn (I don't remeber what the horn was when I measured it)..
    #62
  3. Dieselboy

    Dieselboy Journey not Destination

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    A few pics:

    F8GS Center Panel

    [​IMG]

    F8GS AP1 under center panel

    [​IMG]

    F8GS AP1 under center panel (moved to show wiring)

    [​IMG]

    F8GS Seat

    [​IMG]

    F8GS under seat

    [​IMG]

    F8GS Starcom1 in tail section

    [​IMG]
    #63
  4. JRWooden

    JRWooden Long timer

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    DB:

    I'm not trying to be a dick or anything :lol3 but I'm thinking I would not "lash" the manual on top of the engine computer ... it could provide extra "insulation" in hot weather that you don't want...

    Just a thought ... all free advice is worth the price paid :1drink

    Jim
    #64
  5. sekalilagi

    sekalilagi Been here awhile

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    Hey there Diesel
    I have not much familiarity with the BMW but am quite familiar with CAN bus systems as we've developed 'nodes' for various projects at work using CAN. A couple of things come to mind.

    1. The load resistor in parallel with the relay makes sense if you have disconnected the stock horn, otherwise should not make that much difference.
    2. Clamping diodes on both your relays make sense but you might want to check as some automotive relays already have these diodes built-in. Normally can be seen on the 'schematic' printed on the relay.
    3. The Stebel (at 18A) is probably capable of huge inductive spikes in and by itself. The longer the wiring or more circuitous (no pun) the path between the battery and horn (via relays, and fuse panels) give more opportunity for any voltage spike to be inductively coupled into nearby wiring (including the CAN data lines). We've had inductive loads cause all kinds of havoc on circuits that are not physically attached/connected.

    Here're a couple of suggestions:
    1. Ensure that you have 'matched' the supply and return lines that feed the load to the horn. i.e. you should be able to trace the outbound and return route with as few skips/junctions along the way. Using the chassis to ground the load 'on the way back' is a no-no when dealing with high current, inductive loads. If possible I'd isolate the ground lead for the horn (straight shot to the battery) from the ground leads used for the relay coil(s).
    2. When routing the high current load lines to the horn (via the relay) try to avoid bundling it in parallel with the CAN lines while keeping the high-current leads as short as possible.

    Hopefully the above should do the trick.

    If not, you might consider one of two things
    a) placing a clamping diode at the 'horn connector' i.e. closest to the source of the transient.

    alternatively

    b) Use a TVS (transient voltage suppresor) which will curb the positive swings as well. You would use a TVS in parallel with a 'plain' diode.

    Here's one that should work
    http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=478-2492-2-ND

    That being said, if the wiring (both positive and return) between the battery and the horn are 'clean' and balanced, you should not have to resort to a TVS.

    CAN is pretty tolerant of all sorts of noise but I've witnessed a 30A inductive load generate 400V spikes and even inductively coupled to the datalines, this can wreak some havoc.

    Here's a quickie (!) test, if you feed the horn relay directly with two leads from the battery (and bypass your fuse panel and CAN powered relay) and it helps, it most likely points to noise coming from the wiring and the above suggestions should help.

    The above assumes that firing the horn generates some sort of voltage spike/transient capable of restting the system. It might be worthwhile to check the state of charge of the battery or terminal connections as a weak battery (from loads of testing) can also amplify the symptoms or trigger some other low-voltage related circuitry.

    Hope this helps
    Ken
    #65
  6. Dieselboy

    Dieselboy Journey not Destination

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    Ken, wow, thanks for the input. Not only pertinent-- even bettter, it's lucid.

    You are the second person to mention inductive loads crossing over at bundled wiring. If you look at my pics with the AP1 moved, you will note a white block between the battery and airbox. That box is a multi-prong connector through which I am attempting to wire all my accessories.

    My plan was to have a quick disconnect to allow ease of maintenance. I am beginning to suspect that I need a new plan.

    I still need to get to that oscilliscope and see what the electron beasties are doing.

    It's Tuesday...no way to invest time now...maybe I can get this thing moving again this weekend.

    Stay tuned.
    #66
  7. PackMule

    PackMule love what you do Super Moderator

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    I love this place. :freaky




    :thumb
    #67
  8. Dieselboy

    Dieselboy Journey not Destination

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    AP1 had corroded on the bottom of the circuit board. This tiny detail was repaired by resoldering the board (something for which I definitely needed help-- and I happily recieved.) That and a bit of wiring verification and now the horn, happily, operates through the AP1. I don't fully understand how it was working at all, but it is moot.

    The relays are operating as expected.

    The horn is operating as expected.

    So my saga is now over, except I will be buying a new AP1 (or 2).

    Of interest to all of you, the oscilliscope confirmed that there is no spike coming back into the system from the horn operation.

    On to the next project....driving lights...
    #68
  9. Dieselboy

    Dieselboy Journey not Destination

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    Boston12GS, you win. :beer

    When you reach the end and look back, the path is so clear....
    #69
  10. Dieselboy

    Dieselboy Journey not Destination

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    Jimbo, I've decided to take your observation to heart and have moved the manual ontop of the fuel pump. I'm tired of eletrical issues for now and certainly don't intend to create any more.
    #70
  11. Dieselboy

    Dieselboy Journey not Destination

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    So it wasn't actually the relay...as I re-read this....so credit is misplaced. Nonetheless, much like Columbus, I've given you credit so the holiday will remain in place...
    #71
  12. JRWooden

    JRWooden Long timer

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    Given the price of that little shiny box ... I think that's good plan! :D

    Jim
    #72