Switched Power source frustration ... and the answer is ??

Discussion in 'GS Boxers' started by DownunderBrian, May 26, 2012.

  1. DownunderBrian

    DownunderBrian B2

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    Picked up my 12GS a couple of days ago.. a 2012 ex-demo bike.

    One of my first jobs is Fusebox. I have the box (having researched the various options on here and other sites).

    Now.. the one thing I can't seem to get straight is the switched power source.

    I have probably read every post on this website from the last 2 years regarding this topic.. and searched the FAQ, and the 1200gs.info site, and others. I'm not sure that I've got an answer that I'm totally happy with....but I think I'm close.

    Here's how I see the options...

    Headlight - a number of people say use the low beam, but then I've also read that GSs have issues burning out headlight globes already, plus the computer (be good if it had a name... HAL? LOL) reports LAMPF! for some people after a while with this method. Plus its at the wrong end of the bike... which I could get over but doesn't seem like the best solution.

    Tail light - seems about the same number of people prefer to use the tail light. Closer to the under-seat positioning of the fusebox, so that's good.. but isn't the taillight globe monitored by the computer also?? A read a couple of posts with people having LAMPF! errors with this method too.. d'oh!

    Diagnostic - One of the most popular sources seems to be the blue/green wire feeding the diagnostic socket just under the rear of the riders seat. What a great idea this seemed to be... close, non-essential. But the I read a few dire warnings about this becoming a potential warranty problem, maybe even causing a problem with the diagnostics?? I'll do my own oil and valves, but if I need the BMW guys to plug in and diagnose a more complex problem then I'd like all that expensive electronics (that we pay for in the price of the bike!) to work and for the workshop guys to not give me grief about the mods.... still... it does sound pretty good.

    Under-seat OEM accessory socket - Hang on a minute... just under the tool tray where I'm going to mount my fusebox there's a power socket already... where's the harm in tapping that power for my relay switch?? The workshop folks can't complain because really all I'm going with the accessory socket is powering an accessory (kind of...). No bulbs are going to give me error messages and my diagnostic port with be untouched. Plus its RIGHT THERE in the perfect location :wink:

    Only one doubt remains.... many people have warned AGAINST using this for switched power. "They" say that while the CANBUS is supposed to shut it down in 45 seconds (or something like that) the CANBUS can remain active or even "wake up" if there's a load.

    Really? That really scared me off at first... but now I'm thinking.. does the power really come back on or stay on with a load applied? Isn't that the whole idea of that socket being switched now on the 12GS? (as opposed to being always hot on the 11XX)

    OK, so I've read that the BMW factory battery charger sends a signal to "wake up" the CANBUS to enable the port for charging, but isn't that a different thing to a simple latent load being applied by my snoozing iPod or GPS? (non-BMW). I can't believe the 'switched' accessory socked would come back on becuase it has load. That would effectively make it always hot.

    So now, despite the warnings of some, which have given me flat-battery-while-camping nightmares in my sleep this past week, I'm thinking that the accessory socket is the obvious and best choice for the trigger wire.

    But I'm still a little nervous about those flat-battery warnings! I've only read posts by a couple of people that have used the accessory socket for the trigger wire. Could those people give me an update on how that's worked out?

    .. and perhaps there's a CANBUS guru that can confirm or over-rule my common sense view that of-course once the accessory socket goes to sleep it stays asleep (BMW battery tender secret handshake excluded...)

    Thanks..
    #1
  2. aculate

    aculate Herk, herk,...Ptooey

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    I'm assuming you want to trigger a relay for your fuse box. If you want key-on, key-off with no CAN-Bus delay, and avoiding the diagnostic socket wire, try tapping the wire for the parking light up front.
    #2
  3. marchyman

    marchyman DR and GS Supporter

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    Yes, the GS eats headlamps at the rate of about one per 10-12K miles. It does that regardless of it's use as a relay trigger. Relay trigger current is low enough that the ZFE doesn't know it is there. You won't have a LAMF failure as long as it is only a relay that you are switching. I think it is the best solution because other than a quick flash at power on time the bike doesn't turn the headlamp on until AFTER the bike is started. Turning the key on doesn't cause your aux devices to come on and drain the battery. Given the smallish size of the GS battery that is a good thing.

    As for your accessory socket concerns. The socket turns off from 1 to 15 minutes after you turn the key off. At least that's what it says in my riders manual. From observation I'd say it turns off at 1 minute most of the time. Every once in a great while it will turn off at 15 minutes. I haven't a clue what causes the bike to decide it's going to be one vs another.

    If you are using the accessory socket with a "canbus aware" charger the socket may stay on as long as the charger is plugged in. Or the "canbus aware" charger may not work because you've got extra stuff connected to the socket. I've seen it go both ways. If you don't use one of those chargers or you use one but hook it directly to the battery you don't have to worry about that.

    I don't like keeping things like 100 watts of extra lighting on with the ignition off, even if only for a minute. You might not care. Or you might not be driving aux lighting from your switched power.

    See http://www.snafu.org/pics/r1200gs/2007/0608-wiring/ for one method of using the headlamp to trigger a relay.
    #3
  4. NZ rider

    NZ rider Adventurer

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    I used the accessory socket power supply to power the switched supply on my Fuzebox. It worked fine until I recently purchased a BMW battery tender and plugged that into the accessory socket. The battery charger error light came on and wouldn't go out no matter what I did. I thought the charger was a dud but then remembered the power supply had the Fuzebox tapped into it. I disconnected that and the error went away. I don't understand the logic of this yet and have yet to find an alternative source for the switched side of the Fuzebox.
    #4
  5. marchyman

    marchyman DR and GS Supporter

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    See the link in the posting before yours. My fuzeblock is triggered from the low beam.
    #5
  6. aGremlin

    aGremlin Been here awhile

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    One of my Touratech accessory hubs has the trigger wire tapped into the taillight, without issue...

    I'm not sure where the other one is... heads forward somewhere...
    #6
  7. mikegc

    mikegc Long timer Supporter

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    I changed my trigger from the accessory socket power source to the parking light. It works just fine.

    Mike
    #7
  8. Pete O Static

    Pete O Static Adventure Seeker

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    #8
  9. motomandan

    motomandan Been here awhile

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    #9
  10. mikegc

    mikegc Long timer Supporter

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    Now that is one slick little unit! I wish I'd known about it when I installed souldered my trigger wire to the power lead on the city light. I'll know next time!:clap

    Mike
    #10
  11. bemiiten

    bemiiten League of Adventures

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    Tough choice? Chop into the bikes wiring harness or better yet, draw power through the computer on a un-protected circuit. Or use the protected accessory socket to close a relay. Oh, and the fuse box is a waste too. All the connections under the little screws will all corrode and turn to shit in a few years. Buy your accessories, use the supplied fuses and do a neat wiring job with crimps & shrink tubing that you can put in the box behind the battery.
    #11
  12. marchyman

    marchyman DR and GS Supporter

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    No wiring chops necessary. Not even a vampire tap to spoil virgin insulation in my case.

    Where does the relay go? How many relays? What if your under tool tray box is already full with things you do not want to move. And do you cut shrink wrap and re solder or crimp every time you add and remove a device? What if you add/remove devices on an annual basis? I suppose Fuzeblock terminal corrosion is possible... so is battery terminal corrosion. Simple periodic maintenance will negate both issues.

    My one concern about the specific "Fuzeblock" product is its limited current carrying capacity... 10A per circuit and 30A total. Since I can live with those limits the device works well for me.
    #12
  13. Plane Dr

    Plane Dr Long timer

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    I "tapped" the underseat relay to trigger the "swithed" side of the centech. I have a fused power supply feeding it and I have a seperate fused circuit to the battery with a connector underneath by the back of the airbox. Then I have a high power line for charging and feeding my compressor when needed.

    I feel a single tap is pretty minor. All the sub harnesses are shrink wrapped and soldered.
    #13
  14. aculate

    aculate Herk, herk,...Ptooey

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    Take your time and do the best job you can. Use quality components.

    Solder connections whenever possible, use shrink tubing, armor the wiring with chafe guard, and liberally zip tie to the frame to reduce or eliminate vibrations in your wiring. Route your wiring away from hot spots.

    I use marine grade wire- West Marine's Ancor brand tinned, stranded copper wire, slightly over-sized for the electrical load. It's expensive, but you only use a few yards on a motorbike. Where bare wire is unavoidable, like at the screw terminals of a fuse box, tin the bare wire with solder, then coat it with dielectric grease before clamping it down under the screws. It will work reliably. Even if those screw points corrode after a few years (unlikely), it's a simple job to pull them, clean them, and re-coat with grease. No worries.

    If you slap your wiring together, you'll get what you deserve. Crap job, crap reliability. Your BMW is an expensive machine, do the job once and do it correctly. :deal
    #14
  15. JimVonBaden

    JimVonBaden "Cool" Aid! Supporter

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    Why avoid the diagnostic blue/green wire? It is on and off with the key, and easy access. There is no evidence that it causes issues.

    Jim :brow
    #15
  16. NZ rider

    NZ rider Adventurer

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    My only concern with using the diagnostic blue/green wire is around whether it would cause and issue with the bikes warranty?
    #16
  17. waylongway

    waylongway madmax Supporter

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  18. EggChaser

    EggChaser Been here awhile

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    If you get the BMW auxiliary lead extension/splitter lead wire (Part number in EMEA for an '08 was 61.12.7.712.581, however I don't believe they have changed anything to need a different part) Then you can plug this in behind the under seat socket and then cut the end of the spare tail that this lead gives you and wire this to a relay.

    This means you have not touched the original wiring and can easily remove the modification later. You also have not wired anything but the relay into the CANBUS, as the relay controls the power feed to your accessories. You have also got past the 5A max load on the OEM auxiliary socket.
    #18
  19. bemiiten

    bemiiten League of Adventures

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    Yes, it can. http://advrider.com/forums/showthread.php?t=701671 Then, staring at me BIG AS LIFE was a Posi-Tap that I tapped into the Power of the Diagnostic Plug. My instinct said...unscrew that wire and see what happens.

    OK...you're ahead of me. Yep, the RED WARNING light and BATTERY icon vanished into thin air when I re-started. Yeah...but is the alternator actually charging the battery...this is what I want to know. While the bike was running checking the battery terminals and voila...14.xx volts!

    Geez, Louise. It was the wrong place to connect to power. The high visibility brake lights DID WORK and flash appropriately...but also affected the output of the alternator...resulting in the RED WARNING light and the BATTERY icon.
    #19
  20. Emoto

    Emoto Sure, why not?

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    DownunderBrian, just tap into the back of the underseat accessory socket for your relay signal wire. It'll be fine. I did mine that way in either late 2004 (I got a 12GS from the first shipment to the US in 4/04) or early 2005 and it has been fine.

    For charging the battery, avoid the expensive ridiculous BMW unit and just add a second accessory socket near the other underseat one. Make it fused, but wire it straight to the battery. Use whatever charger is appropriate for your battery type through that socket. It is also nice to have a second socket in the event that you and a passenger both need to plug in electric garments, because the canbus controlled socket is sensitive to draw and will shut off if you pull too much juice through it, so running multiple electric garments off of the factory socket can be problematic.
    #20