High level rear light on CanBUS bike?

Hi All,

Does anyone know of a gadget that would allow the connection of a high
level brake light on one of the modern bikes (a BM in this case) that
use a single 21W lamp for tail / stop light please?

It's for a mate and he just wants the lamp (or strip of lamps in this
case, mounted in the top box) to come on in synch with the std brake
light.

All the best ..

T i m

 

Try this:

http://bmwsporttouring.com/ubbthreads/showflat.php/Cat/0/Number/966215/Main/965780

I haven't been paying much attention to CANBus before now, but Jesus,
CAN'TBus or what? It's like Vista for bikes.

 

Well, I just had a quick google and received the distinct impression that
the implementation, on BMW bikes at least, was a pain in the arse. Examples
of CANBus getting its knickers in a twist over such things as such battery
chargers, spotlights, high-power headlight bulbs and so forth.

 

That doesn't differ from multiplexed car wiring one bit...

 

Thanks for that.

I can see how some of it could be a good idea, especially as these
machines have more and more options / functions. Bulb failure
indicators being one that could be considered a safety feature for
example?

<weg> Would I buy something that complicated ('complicated' being not
having access to the tools needed to diagnose / configure this stuff)
not till I had to I wouldn't.

But then I guess it's just progress. I remember fitting the Luminition
optical ignition points replacement unit to the kitcar when we built
it 18 years ago and haven't had need to touch it since ...

All the best ..

T i m

 

Not just cars. I've seen it used in industrial machinery, too.

 

I don't recall plain-Jane CANbus causing particular problems, though I
wasn't directly involved. It's possible that extra security stuff for
automotive use - particularly bikes but remember that Audi bug - has
buggered it up.

 

The CANbus itself and indeed the entire system works pretty well. The
problem is that folks expect to be able to replace bulbs with those of
different wattages, and are being caught out when the smart switch sees
a different load than it expects, and the controller shuts down the
circuit or turns on a warning light. If I wanted to add electrical
gubbins to a CANbus bike, I would attach a fuse panel directly to
the battery and bypass the CANbus system.

 

Aah, of course: one power circuit = one fuse, unless you have fuses
scattered all over the place.

 

That in itself can throw up problems as the system detects an
unidentified power drain ,

--

 

Which is what my mate intends to do for all the std auxiliary
requirements but this brake_light_only trigger is a bit more
complicated.

I guess we don't want to load the bus by much or it might cause a
false fault trigger so that means some form of high input impedance
device driving a suitable output device (relay?). Nor do we want to
inadvertently 'earth' something so a floating / isolated input might
be best.

What we don't know is what's going on, what makes this 21W lamp go
from the equivalent light output of a 5W for a tail light to the full
21W for a brake light?

I'm guessing it's a 'simple' voltage step, either outputted directly
from the controller module or by the 'shorting' of a load resister
(simple but less efficient) but it's not impossible that it could use
some form of PWM?

I though this buss stuff was similar to USB .. a host 'talking' to
'devices' and those (coded) devices (typically micro relays in this
role) doing what they were told via data on the bus?

The actual energy being fed to the lamp should be fairly easy to
'detect' but we just need to know how to make a suitable circuit to
match (anyone know please)?

All the best ..

T i m

 

Using the patented Mavis Beacon "Hunt&Peck" Technique, Mark Olson

A rather easier way might be to flog the piece of pointlessly
over-complicated shit and buy a bike.

--
Wicked Uncle Nigel - "He's hopeless, but he's honest"

WS* GHPOTHUF#24 APOSTLE#14 DLC#1 COFF#20 BOTAFOT#150 HYPO#0(KoTL) IbW#41
SBS#39 OMF#6 Enfield 500 Curry House Racer "The Basmati Rice Burner",
Honda GL1000K2 (Fallen apart) Suzuki TS250 "The Africa Single"
Norton 850 Commando Kawasaki GTR1400

 

I'll go with that .. ;-)

Ok ..

Ok ..

They are nearly my exact words to my mate when he first asked last
night! ;-)

Yep. Would it just need any low pass > comparator decoupling to be
fairly 'tight' so-as not to hang on to the signal once it drops back
to tail light?

It does indeed, thanks Mark.

All the best ..

T i m

 

I'm not sure that's a solution in this case, partly as he hasn't
bought the thing yet and partly because he *needs* something like this
(I think his current ride is a K1200LT) for the fairly enormous miles
he put's on the things each year.

All the best ..

T i m

 

Using the patented Mavis Beacon "Hunt&Peck" Technique, T i m

There's still time! Thank ged!

See comment above.

--
Wicked Uncle Nigel - "He's hopeless, but he's honest"

WS* GHPOTHUF#24 APOSTLE#14 DLC#1 COFF#20 BOTAFOT#150 HYPO#0(KoTL) IbW#41
SBS#39 OMF#6 Enfield 500 Curry House Racer "The Basmati Rice Burner",
Honda GL1000K2 (Fallen apart) Suzuki TS250 "The Africa Single"
Norton 850 Commando Kawasaki GTR1400

 

Oooo, (at first glance) that looks like it may well do the trick!

I'll pass the link on and let you know what happens.

All the best and thanks ..

T i m

 

I've just received an eMail from my mate with an attached eMail from
someone who knows and it's exactly as you (and I) speculated and PWM
;-)

It also appears it's two single filament lamps (presumably in
parallel, this is the K1GT we are talking about specifically here).

So, what is a popular robust opto isolator these days Mark .. ;-)

All the best ..

T i m

 

Ok ..

Understood.

Thanks again Mark and all the best ..

T i m

 

Got me, guv. Honestly I can't see any benefit at all to the user
in using CAN bus technology other than perhaps it allows some
improved diagnostics, such as indicating a burnt out taillamp.
On a motorcycle it's pretty pointless, as you say. Leave it to
BMW, lately they don't seem to be able to resist adding needless
complexity.

You might well change your tune about KI-PASS and all the related
nonsense if it goes tits up and leaves you stranded. There seems
to be a fair amount of teething pain associated with all the new
tech toys on the GTR1400.

 

Using the patented Mavis Beacon "Hunt&Peck" Technique, Mark Olson

oh, doubtless. I'll whinge like a mofo when it fails.

--
Wicked Uncle Nigel - "He's hopeless, but he's honest"

WS* GHPOTHUF#24 APOSTLE#14 DLC#1 COFF#20 BOTAFOT#150 HYPO#0(KoTL) IbW#41
SBS#39 OMF#6 Enfield 500 Curry House Racer "The Basmati Rice Burner",
Honda GL1000K2 (Fallen apart) Suzuki TS250 "The Africa Single"
Norton 850 Commando Kawasaki GTR1400