Re: [gti-vr6] NewBeeetle (off topic)

[Arthur Emerson <emerson@eideti.com>]

deecee@exit109.com wrote:
> 
> The engine is a new design 2.0. Because of the low hood the engine is 18mm
> shorter in height.

And they're gonna get a VR6 syncro in there???  Scratch one
rumor.

> There is a new wiring system which uses new technology called CAN-bus.
> 
> Controller Area Network bus.
> 
> This new technology uses fewer wires and accomplishes this serial data
> transfer via CAN-bus.

Wild!  How does this differ from the current VW/Audi systems?
My understanding is that the current systems are on a network too,
and you're addressing the individual components when you query
the car with the VAG 1551.  If I remember correctly, you first
send down a test group number, which is probably the controller's
network address.  Then, you send commands to the selected controller.

This kind of technology has existed for 20 years in the instrumentation
business, going back at least to the IEEE-488 bus.  Sixteen devices
(4 bit address) could sit on the bus, and each device could talk
to every other one.  The Commodore PET, VIC-20, and C-64 used this
bus to connect printers and floppy drives.

I think that VW is making a great advance here, and don't see any
big problems on the horizon.  To the contrary, less wiring means less
chance of failure.  When a controller won't communicate, you
just have two wires to check before you replace the unit.  On
startup and periodically afterwards, the main computer in the car
can poll the other ones to see if they are functional, and
immediately alert the driver if they are not.

> Because of this new system there are only 2 wire
> bus to handle all the information to all of the ECM's at the same time
> instead of several wires between each module.

It probably would have been prudent for them to use 4 wires in
a dual ring, like ATM.  If one path goes down, the car can still
run, and you can still query the controllers.  One step at a time,
I guess.

> There are several pages that are devoted to the electrical system. I feel
> like I can get a job with Nasa after working on this car. It has the
> potention to be an electrical nightmare.

I might take back all of the bad things I've ever said about it.
It looks like they set it up to be self-diagnosing.....

- -Arthur