CAN-BUS and OBDII. What is it... why?
What's the future?
What about WiFi in vehicles (for diagnostics!)?
Telematics? Charging cautions!
(with an addendum for the Nerdy about other systems)
© Copyright, 2014, R. Fleischer
Can-Bus is the same as CAN-BUS, CANBUSS, CAN-BUSS, Canbus, CanBus).
OBD means On Board Diagnostics. OBDII or OBD2 is the second version,
in very common use now.
Can-Bus is a version or type of OBD.
Can-Bus is a method, hardware & software; to enable communications between 'electrical &
electronics things' on your vehicle; these 'things' can also be mechanical. Can-Bus stands for
Controller Area Network, & the 'Bus' part is explained later herein.
As you will see in the section on the future, it can do a lot more than just in-vehicle communications.
While Can-Bus will be mostly discussed here, as it is installed by BMW in your bike, etc., the
information is similar for any system such as all the varieties of OBDII....all modern cars have
such a system; & a diagnostic plug to access it. In a GENERAL sort of way, Can-Bus systems
have the ability to transmit information between components at high speed, & to actually make
changes in the operation of items. Again, in GENERAL, OBD can do some of that, but mostly it
is seen by most as just diagnostic, retaining information in memory, until downloaded for diagnostic
work, or such work can include erasing memory, modifying how systems work, etc. But, that is
not really true....it can be a serious part of actually operating the vehicle systems.
BMW decided to reduce the number of electrical wires & connections & hopefully reduce
electrical problems, by operating just about everything, to the extent possible, using digital
electronics. There are some definite advantages, such as weight saving; manufacturing labor;
& the potential for much higher reliability;...as only a few wires are needed for most anything. In
addition (and more importantly), the ability for the computer(s) to monitor & talk to each other
about just about any function, & particularly in a very short time period, is greatly enhanced.
There are other reasons for going to something like Can-bus. Vehicles are becoming vastly
more complicated, so more & more computers or mini-computer elements are needed to
monitor, produce or accept information from each other. There are other reasons, which I will
also get into.
In the Classic K bikes (K75, K100, K1, K1100) there is monitoring of many things going on all
the time by the central computer, in order to have the ignition & fuel injection operate at near
optimum, all the time. These bikes were fairly simple, compared to later BMW models....but
many including braking system computers & hardware...for example, there was, on many models,
an ABS braking system, to control wheel spin & make emergency braking much better than
most riders could do manually.
Later bikes than the K1, K75, K100, K1100; sort-of beginning with the K1200, had much
fancier systems available.
The ABS system can be modified to include throttle, ignition, & even suspension items, the
result of all these things could be ...and is....stability control systems, & a lot more.....and
these are now STANDARD on many BMW bikes. Braking in corners is no longer as fearful,
power can be used much better without wheel spin and wheels slipping, ETC...>LOTS OF ETC!
Traction & stability control & ABS all require fast information processing, &
electronics is absolutely necessary for these functions.
A problem that arises from Can-Bus & other such systems, is that the electrical system is,
to quite some degree, no longer relatively easy to modify with farkles, changes, & add-ons.
Adding an electrical outlet jack might cause problems. Typically, the answer is to wire
accessories directly to the battery, usually via a separately added fuse or fused panel. Still,
there can be problems, depending on what item is added, and how wired, even if to the battery.
It is more than even that. Because of how various sensors 'report' to the computer(s),
the battery condition becomes more important than previously. Eventually we will
see monitors for the battery, reporting to the main computer, not only the state of
battery voltage & actual charge, and complex charging characteristics....but soon
the systems will be able to identify a battery with higher 'impedance' (something like
resistance), which would allow Can-Bus and other 'signals' to be disturbed by the
Bosch invented Can-Bus in 1983 for use in Mercedes cars; & actual use began in the late
1980's. Can-Bus is just one of several 'protocols' of the OBD-II system. Your car likely has
"OBD"; that stands for On Board Diagnostics, & it is standard now for all cars...the latest
version is OBD-II. A technician can connect a 'reader' (or other perhaps more sophisticated
gadget) to an electrical plug in your car. He can read out problem codes...as well as
non-problem codes. He can get a lot of information about the engine; transmission, brakes,
cooling system; & much more. A simple version was in the early K bikes; later versions are
much more sophisticated.
The computer(s) provide the information. Information can be real live time, or in memory.
With the some types of 'readers' a technician can actually make adjustments & incorporate
computer updates. Your BMW dealership has sophisticated reading/updating/adjustments
computers to analyze and modify your vehicles systems. Modifying the computer functions
is called 'flashing'.....as the information is transferred to something akin to the flash memory
chip in your personal computer. Many times a manufacturer will offer updates to correct some
problem or other need. These updates are obtainable by authorized repair centers. For
BMW motorcycles, there are aftermarket readers that can do many things besides reading
codes and displaying those codes. Actual changes can be made.
Various Governments have mandated these methods of computer readouts in your vehicle.
The USA Federal Government mandated that the USA comply with the International Standards
for OBD & Can-Bus, which are closely related. I think this happened in 1994. It was TEN
years, before BMW incorporated full-blown Can-Bus into its motorcycles. Prior to that, BMW
had its own versions of OBD, incorporated into such as the Jetronic & early Motronic systems;
primarily for error or malfunction codes, although there were some outputs & inputs....and
you'd need the fancy BMW dealership machine ($18,000.00 I think it used to be, long ago &
equivalent to a LOT of $$$ now-a-days) to do everything possible.
At one time there was quite a bit of chit chat, in various media, about the FACT that as car
computers got sophisticated enough, just about all of them would 'record' certain things, that,
if read-out properly, would show the last so-many-seconds of vehicle functions, before some
event...like the deployment of the airbags; such as speed, accelerator movement; if the brakes
were applied and when, ETC. Yes, this is not only possible but it IS being done in all cars...so,
yes, it is TRUE. Your car's computer WILL, and DOES, record this. Common slang calls
the vehicle computer storage area for this, a 'snitch box'. Insurance companies are interested
in readouts. So are Authorities, like the police. Sooner or later, it will be incorporated into just
about all motorcycles. This is NOT pie-in-the sky, it is here NOW!
The Buss (Bus), somewhat simplified: An electrical bus is a common
interconnection area, point, and/or method of transportation of information or just plain
Very simplified versions were used in large trucks & in airplanes since the 1930's, maybe before.
In that type of usage a bus was typically just a multiple connection point or perhaps a strip of
metal with many connections to it, for a group of common-connected wires. There might have
been more than one such bus, with an interconnection switch (usually a circuit breaker) allowing
them to be separate, or connected to each other. Thus, 'systems' in the aircraft or truck, etc.,
could be separated, or not. It was common to have a battery hot bus & a battery ground bus.
This bus idea is done in your HOME, by multiple connections in the power-meter box, for grounds,
hots, & neutrals. Your home may also have HIDDEN 'indicating' type of fuses, and other things
that report on certain conditions. Thus, the Buss effect of multiple connections points AND
information points or devices, is fairly common on even very old equipment.
These uses of Buss (having nothing to do with the BUSS COMPANY, which makes fuses, etc)
are very simplified uses of the term of bus. It gets much more complicated with the usage &
A vehicle bus carries a lot of people, so many think that the word was adopted for the multiple
electrical signals that can be on a single wire. An analogy of that thinking might be the TV cable
coming into one's home....many dozens of programs on the same single wire.
In actuality, the word goes way back, when buss, spelled that way, was used. Your dictionary
may not show that. Although RECORDING status of some things in aircraft and big trucks was
quite primitive, and mostly NOT electronic way back in the thirties, it did happen, mechanically.
In some instance an mechanical record was made by electrical means.
In a way...kind of exaggerated here, one could think of that just mentioned TV cable company's
single coaxial cable wire coming into your home as a bus (buss, if you want that spelling), carrying
all those differing TV & audio programs on just one wire, (really two wires, an inner solid wire &
the shielding around it). So, warping the use of the term, that could be a signal bus wire. In your
vehicle, in the electrical system, any particular BUS (there may be many) might be just ONE OR
TWO (could be more) wires, carrying all sorts of digital or analog codes, from MANY devices
connected to just those two wires. Digital (& occasionally analog) coding (digital coding is TIME
related) separates the functions. There are far more complicated methods of transmitting data
in your vehicle, using a few wires...but won't delve much deeper into this.
To spell this out a bit differently; a digital bus allows multiple packets of information, from different
sources, to travel down one path (possibly of more than one wire), simultaneously; in a time-
sharing method. Keeping with the analogies, the INTERNET is really a bus type system, as
information travels in packets....
yes, your E-mail is broken up into many packets; same for website's, etc....as transmitted over
the Internet, or, World Wide Web. The internet uses coding & time segments to be sure the
needed/wanted information goes to the correct place. This is VERY similar to OBD & Can-Bus,
and the other types described briefly later in this article.
The more recently a car and motorcycle year, the more computerized items that are typically
present. Many 'mini' computers are used with many functions & devices. In some cars, one
MAIN computer runs & monitors everything, with maybe some peripheral small computers
doing specific things that are not capable by, or for other reasons not inside the main computer.
The TREND for a long time was to greatly increase the number of small computers in a car.
In recent years this has cause innumerable problems with costs, so nowadays the trend is to
use less individual computers by expanding the main computer functions and abilities. I am
sure this will continue to be the case.
The first motorcycle to have Can-Bus was probably the Ducati 999 back in 2002. BMW
started it with the R1200 in 2004. So, the Classic K-bikes did not have 'real' Can-Buss.
Can-Bus allows most all the various computers (& things that are peripheral, but not a computer)
to 'talk' or 'communicate' with each other in both simplified AND complex manners. This means
that NEARLY EVERY electrical device on your bike could be connected to the Can-Bus system,
which CONTINUOUSLY & RAPIDLY monitors nearly everything. Since most anything
mechanical, can be made to produce an electrical signal from sensors, EVERYTHING can be
monitored and dealt with by the vehicle computer(s) at VERY high speed. In many instances
the limiting function of some action is how fast a mechanical device will produce a change or
force, etc., once it receives the command by the computer to do so.
The system can also monitor current flow, voltage, etc. If you tried to tap into the
electrical system for an extra electrical gadget, Can-bus might complain...in essence
the Can-Bus computer thinks, rightly or wrongly, that the bike has a problem. It might
even record the problem, & MIGHT give you a visual signal that all was not well. If
the load was egregious enough, the bike might not start ...or otherwise be not rideable.
Some ABS systems talk back & forth with the computer that runs the engine itself. It is possible
for the ABS to monitor acceleration or other speed conditions or events, & then with other inputs,
the bike might have traction control applied. That is already done on cars & a few bikes...and
will be appearing on more & more bikes in the future.
Problems with CanBus, as far as vehicle owners are concerned, is USUALLY that we cannot
just willy-nilly connect up electrical gadgets, or modify the electrical systems so easily anymore.
We also are more likely to be needing a dealership to read codes & find problems, with fancy
expensive BMW-supplied test equipment...because when the bike stops running, or has another
problem....we will be much less likely to be able to fix it ourselves. You can imagine the situation
when the warranty runs out. Note that it is entirely possible that the systems will be so reliable,
that many electrical problems seen in the past will be eliminated. In MY mind that is a BIG maybe.
So far, the record tends to show an increased reliability, over-all. That is to be expected...
especially when the vehicle is new, or nearly new.
We can still analyze (within limits) the Classic Jetronic & first two generations of Motronic
computers in Classic K bikes, but it is more of a hassle with the later bikes. There will
undoubtedly be plenty of experimentation done & ideas & tests posted on various LISTS,
Forums, ETC., on the Internet, regarding problems, electrical measurements for such, etc.
For now, the primary method of adding farkles, etc., to Can-Bus bikes will be an
added fuse panel & connections directly to the battery.....plus some few items
containing special Can-Bus compatible circuitry.
DE-sulfating types of battery chargers:
What the heck?
Why do you need to know about battery chargers in a Can-Bus article?
There are smart chargers that have a de-sulfating mode. These chargers are generally
OK for use if the battery has...MAYBE... a quarter charge.....or more. De-sulfation chargers
work, sometimes, but if the battery charge was quite low for any goodly period of time, these
chargers, IF THEY WORK, will be VERY UNLIKELY to give very much more battery life at all,
compared to you using a standard charger, or a smart charger without de-sulfation protocols,
in trying to resurrect the battery.
WARNING!!!! If you use the de-sulfating mode of a charger on a battery that is fully
connected to your bike's wiring system, the very high voltage (as much as 25 volts
spikes!...and in some instances, much more of a 'spike' that is very short in time)
from the charger CAN INJURE THE BIKE SYSTEMS. THIS IS PARTICULARLY SO
AND CAN BE VERY EXPENSIVE for YOU....ON CAN-BUS BIKES!!!! It is potentially
bad for the motorcycle even if the ignition key is off. I highly recommend that you
be very prudent & NEVER use de-sulfation MODE on a Can-Bus bike that has the
battery installed and fully connected.
If you want to try the de-sulfating mode, DISCONNECT the battery from the bike!
IF you remove the battery from the bike, or at least disconnect it (all wires to the
negative terminal will do if careful NOT to connect the charger negative to the bike
in any way), then there is NO problem with using a de-sulphating mode charger
on ANY bike.
DO NOT use such a charge mode with LITHIUM batteries!...EVER!!
For another way of looking at Canbus, try this article:
The future, ...here's where I predict what is going to happen:
The future will be electronics. It has now been many years since cars got fuel injection &
ABS brakes. GM's ON-STAR two-way communications (with On-Star's ability to do all sorts
of things TO your car) was put into its cars. Now, many cars are being equipped with versions
of what ON-STAR does, under various names, & tying it to CAN-Bus/OBDII.
Everything is being integrated.
Your future vehicle will not only record many things, such as your speed, when and how
you brake, etc....., but will use GPS to transmit your speed and location to receivers located
alongside roads. Your vehicle ID will be transmitted (license plates are NOT needed, but will
likely be kept around for a very long time).....as will be information of exactly where you are...
how many passengers, their body weight or retina ID (the system will know WHO was driving).
OBD/Can-Bus will be welcomed, over-all, by vehicle owners, because of all the sophisticated
things it can do, like helping prevent skidding on slippery roads, help with braking, etc....but it
will be intrusive, reporting your & your vehicle's actions in depth & ways you may hardly believe.
You will become somewhat more bound-to your vehicle brand dealerships because they have
the full diagnostic equipment (which will reprogram your vehicle computers when required).
This ability will tend to remove what some independent shops are able to do for you, thus help
push you to the Dealership. This will be fought by the Independent repair centers lobbyists,
and they will tend to win, partially. The "Independents" will continue to be with us, for decades
to come. Vehicle manufacturer's will continue to find ways of reducing the use of Independents
by vehicle owners. It will be sometimes effective, at other times not so.
The system of reporting, & retaining customers, advertising, features, etc., will be lumped by
industry into a single word: Telematics.
Vehicle makers will view it as a marketing tool, to improve customer retention rates, for future
vehicle purchases, etc. Telematics is happening right now!!!
Besides Big Brother intrusiveness into our lives in countless ways, Telematics will be used by
insurance companies, law enforcement organizations, regulators, etc. It may be used by
thieves, hackers, etc.
Eventually, the OBDII port (a multi-pin plug, usually located under the dashboard) will be
eliminated in favor of WIRELESS transmission of data. For the near term, I expect the OBDII
port functions MIGHT be only accessible to outside interests upon your approval, already some
of that is happening with On-Star, which you may be familiar with in GM cars. I will get into this
a bit more in the next section; WiFi.
Wifi: This may surprise you.
Cars are NOW being equipped with very complicated electrical & mechanical monitoring systems & new designs for starter motors, alternators, air conditioners, etc...& almost anything else, that might somehow, affect emissions, fuel mileage, & MANY other things). Sensors WILL monitor the number of battery starting cycles, temperature of the battery, voltage & capacity of the battery, how long the starter motor was engaged, how fast the battery was recharged, etc. That information will be transmitted by WiFi, to the nearest reception point as you travel. It is possible it can be cell phone towers, equipped to monitor that frequency band; or, by other means. Security of communications will be built-in. When your battery is nearing its calculated end of life, the vehicle's computer will RECEIVE that information, & it will be displayed, somehow. You can expect monitoring of hundreds of things in your vehicle, within a few years. MY understanding is that, initially, GM will give you the option of turning on the system for these things, or not. Privacy could be involved, heavily. You probably already know that the computer in your car will RECORD the speed & some other things, for the last, say, 45 seconds, before the airbags inflate in an accident (or, other reason for the recording). This computer portion is often called a 'black box', & is often called a 'snitch box' & insurance companies can usually get the information. This is VERY similar to the data-recording boxes used in Airliners, except yours will not be so environmentally protected. Thus, in a Court of Law, or
in negotiations with insurance companies, THEY could find out what your speed REALLY was, if you used your brakes, and how and when, ETC. In fact, they could probably show what road, where, accurately, to a FEW FEET, and MANY more things. They WILL be able to print-out your ACTUAL driving habits for years/miles/whatever. YOUR insurance premiums WILL BE based, at least somewhat, on your Car's OWN REPORTING. Further, this sort of measurement and reporting will be tied to YOU in some way, so it will apply to rental cars, rental trucks, wherever you are, at whatever time of day...month...year....etc. This IS COMING, in even greater depth, in MY opinion. While the new systems & parts "condition monitoring" is to be a separate add-on, WiFi transmitted & received, I am 100% certain that it will be combined with the existing CanBus/ OBDII, ETC. Many things will be coming, once this system is fully in-place, such as driverless cars being much more popular; automatic transmittal of breaking of speed laws, & LOTS MORE. Eventually, NO ONE will be able to operate a vehicle on public roads without his/her IDENTITY known to the vehicle's computer, with that information transmitted to 'the cloud'. They will find a way to include old vehicles too. Privacy will be greatly reduced.
This is not wild guessing. It IS, NOW, built into quite a few cars. In fact, a very basic 'learning' mode for cars started a long time ago; first with a re-learn mode when the battery was replaced, or went dead and was recharged.
let your imagination have fun...
For the NERDY (but with a bit of information anyone might want...such as on
the GS-911 instrument you can purchase):
IN GENERAL, whether the system is CAN-BUS, or, some other type of system, a primary
function of the systems ORIGINALLY was to flag problems. Originally, these systems
were designed to give notification to the driver/rider/shop mechanic/; when EMISSIONS
would be increased by over 1.5 times the Federal Test Procedure (FTP) limits. Indications,
memory information on problems, & LOTS more, & now-a-days having to do with much
more than just emissions, are presently in use. Note that safety & other things, also are
part of OBDII, & nearly every other system used on vehicles. Various types of
ON-BOARD-DIAGNOSTICS are used INDUSTRIALLY for process controls, & very much
more..not hardly just in vehicles. In the following, I will discuss use of various systems
only for VEHICLES, but some are used for industrial purposes as well.
There are quite a few variations of what I have almost generically calling CAN-Bus and
OBDII. I won't get into them too much here. CAN-Bus is used for MANY things, not just
the main engine computer. Examples for cars & trucks might be such as door functions,
climate control, etc. Regular CAN-Bus itself has limitations. Its information speed is
limited to 1-Mbit/s. I wrote Mbit/s that way on purpose, because this is megabits, not
megabytes. A manufacturer certainly does NOT want to try to use a CAN-Bus
anywhere near that speed, for safety & reliability. Can-Bus does not work all that well
when higher speed real time data is needed, particularly over longer distances in the vehicle.
I'll restate this: One of its limitations is the real-time speed at which data can be moved
about. With Bosch's Can-Bus, the information signal is sent down the wires in 8 byte
format. There is no theoretical limit, at least in the official specification, for a maximum
number of information nodes, but, for practical reasons 32 is about the limit. CanBus is
a SERIAL information standard; the specification is complex, but allows for priorities.
Serial means that you can only have one type of information being worked on
at any given instant. While the speed that processing of information is done would
appear to be very fast & more than capable of most any vehicle function, that is not
As vehicles become much more complicated, such as incorporating things like
Collision-Warning Systems, Can-Bus will have reached its practical limits. In some
instances, combinations of various methods are used..... and even the use of
multiple CAN-Bus systems!
Due to speed & capacity limitations, other protocols have not only been proposed, but
are already in use. A short list of these is: FlexRay; JASPAR, LIN, SAE J1850,
AUTOSAR, MOST, & even the computer FireWire (1394) standard. MOST, which
stands for Media-Oriented-Systems-Transport, is already in wide usage in European
cars. Toyota probably has already begun using a 25 Mbyte/s version of MOST in its
Prius. Yes, 25 mega-BYTES. MOST in its revision 3 specifications will allow
150 Mbit/s networks.
FlexRay is already in use on BMW's X5 and 7 series. FlexRay defines a dual-channel
10 Mbit/s data structure....and the channels can be used in a redundancy method.
FlexRay use will probably (?) be used by BMW since they are members of a FlexRay
Consortium: BMW, GM, VW, Daimler-Chrysler, Bosch, etc. FlexRay is much more
expensive than Can-Bus, but prices are coming down.
CAN (Can-bus) will likely be THE choice for many vehicle networking nodes until maybe
year 2017 or somewhat beyond. This is my best guess. CAN works with SAE's J1850
Bus specification, which is widely used with OBDII. The SAE has various Bus
specifications, that is only one of them.
That DOES mean that OBD readers MIGHT be able to be used with your BMW
motorcycle that has Can-Bus.....but the information, & how to go about using it, has
not been widely published. There are specialty readers that will read the BMW vehicle
information. The GS-911 is THE diagnostic tool that 'even you' can purchase. It reads
BMW motorcycle codes, can erase fault codes, etc. It is VERY versatile in what it can
do. It is available from Ted Porter's Beemershop. http://Beemershop.com
The GS-911 has limited abilities for the OLDER BMW motorcycles. That is: It has
limited functionality on the Classic K bikes, such as K1, K75, K100, K1100. The
following linked page will detail what bikes it works on, and much more:
Microprocessor Control Units (MCUs) are plentifully used in FlexRay networks. As
more are used, perhaps as ECUs (electronic control units), costs go up, and so
does complexity....as well as capability. The trend has been towards modular units,
each controlling sub-units.
For the ever-so-nerdy, the LIN bus has the lowest cost per node. It uses serial
interconnections, the maximum speed is 19,200 baud...and is often used as a
With today's automobiles.....and now motorcycles....requiring hundreds of megabytes
of software code, ....new standards are proposed fairly often. Just which ones
become popular, is the question. It appears that of the several mentioned above
just about all will become standards.
For another way of looking at Canbus, try this article:
Initial release 10/17/2009, to K-bmw Internet Mailing List
10/19/2009: Edited and made into this website article
10/21/2009: Added the ADDENDUM
05/01/2010: Simplify a bit, and update
05/21/2011: Small additions and very minor clarifications and emphasis here and there.
09/22/2012: QR code, google code, very minor other things
04/03/2013: Add link: http://www.bmwra.org/otl/canbus/
01/12/2014: Add section on the future & revise entire article for clarity & more information
08/16/2014: minor updating.
12/07/2015: major addition re: WiFi reporting
01/18/2016: Add de-sulfating mode cautions for smart chargers.
01/28/2016: Meta code updating. Narrowing article. Horizontal line function changed.
Update article. Increase font size for readability.
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