Sorry about the crosspost, but I own a Pontiac and a Subaru, and this
topic is relevant to both anyways.

So I recently got myself an OBD-II car code scanner cable for my laptop,
and during research I found out that all cars after 2008 will have to be
CANbus compliant. They made a big deal out of specifying what cars prior
to 2008 are already CANbus-capable. I didn't want to have an obsolete
tool for any future cars I might buy, so I looked up what the
differences were between CANbus and OBD-II. After reading up various
websites about CANbus, such as this one:

http://en.wikipedia.org/wiki/Canbus

So I found out that CAN stands for Controller Area Network, and that it
seems to be a networking specification for car components, similar to
the network specification that connects your PC to the LAN. It doesn't
seem to be specifically about diagnosis of faults in your car, just
general internal communications between components. So I'm thinking do I
really care if my fuel injectors communicate with my power window motors?

Basically, all I wanted to know was how does it affect me? Do I need a
new cable to connect to the car, or do I keep using the existing OBD-II
cable? My feeling is that nothing has changed, and that they just added
a few more codes to the standard OBD-II codes (the P0xxx codes) and the
proprietary manufacturer codes (the P1xxx codes). I think all they did
was add some additional diagnostics codes to check whether network
connections are working between the components on a CANbus, but the
format remains the same. The additional codes are the Uxxxx codes, as
listed in this link:

http://www.aa1car.com/trouble-codes/can_codes.htm

I think this might be what the case is, just some additional codes. But
the method of connection is exactly the same as before, and that we're
not really going to be plugging our scan tools directly into the CANbus.

Yousuf Khan

Hi Yousuf!

On Thu, 30 Apr 2009 10:37:42 -0400, Yousuf Khan <bbbl67 (AT) yahoo (DOT) com>
wrote:

My understanding is that the CANBus allows you to do things like use a
laptop and Bluetooth adaptor to communicate with the ECU (as opposed
to the hard-wired ODBII cable), allows the tire pressure monitors to
communicate with the car instrumentation, etc.

I'm at least reasonably certain that the presence or absence of the
CANBus hardware will not affect the functionality of the "standard"
ODBII interface.

But I've been wrong before, alas ;-)

You might wander over to one of the MegaSquirt forums (MegaSquirt is a
DIY stand-alone engine control system. http://www.msefi.com/index.php)
and ask the ECU gurus over there; I seem to remember some discussion
regarding incorporating CANBus into the MS platform. Good chance you
will learn way more than you ever wanted to know about the subject.

There are probably some OBDII forums out there as well, but I'm not
familiar with any.

If you get satisfactory answers, do let us know what you find out.

ByeBye! S.

Steve Jernigan KG0MB
Laboratory Manager
Microelectronics Research
University of Colorado
(719) 262-3101

S wrote:
Using a Bluetooth connection as your wireless OBD cable instead of a
real OBD cable seems a bit far-fetched. I'm sure that such a module can
be built and connected through CANbus, but I don't think that's an
existing functionality of CANbus.

One of the examples of Bluetooth-CANbus usage in automobiles that I've
heard of is a bit more mundane. In that example they talk about using a
Bluetooth adapter to connect a handsfree microphone to the car's speaker
system. When a call comes in the handsfree automatically mutes the car
stereo through CANbus. Another CANbus usage might be to tie the car
stereo volume control into the engine rpm and road speed sensors, to
auto-adjust for road noise.

Another usage might to tie a taxi meter into the road speed sensor.


Okay, I'll try there.

Yousuf Khan

S wrote:

It would seem that that's not the right forum for asking these sorts of
questions, since it is a pretty product-specific forum.

Yousuf Khan

Yousuf Khan wrote:
Cable? What interface box you got? ELM327? Or sosmething else?
All you need is Canbus compatible interface.

Tony Hwang wrote:
Yeah, it's a USB to OBD-II connector that fits on a PC or laptop. I
think they call it ELM327 or something like that.

Yousuf Khan

Yousuf Khan wrote:
327 is compatible with Canbus.
I use it with my notebook. Works well.
Fixed a few CEL prblems such as knock sensor, O2 sensor, misfiring
cylinder, etc., etc.

Tony,

I have a question. I have been looking into an OBD-II interface; but it is
a case of the more I read the more confused I get.

Which unit do you have?

Comments and suggestions welcome.
"Tony Hwang" <dragon40 (AT) shaw (DOT) ca> wrote

Jonathan Heard wrote:
ELM327 and I use USB connector. I had ELM325 with serial connector but I
replaced it.

On May 1, 10:34*pm, Tony Hwang <drago... (AT) shaw (DOT) ca> wrote:
So is the ELM327 the little chip that's inside the OBD-II cable?

Yousuf Khan