Ferrari Mailing List: Re: Need help with stereo in Ferrari

[Jim Conforti (lndshrk]

At 11:06 AM 3/8/2009, you wrote:
> I recently attended a diagnostics OBD II class covering the new onboard
> communications protocol called CAN (Controller Area Network). For 2008, CAN
> is used on all U.S. passenger cars and light truck.
>
> Found a break in a wire?  Want to repair it?  This touchy system requires an
> exact number of twists per inch, same length and gauge wires and don't even
> think about splicing unless you hold an ME in advanced auto electronics.

  Doug,

  Just FYI - this has to be nonsense that some regulatory agency has
  come up with.  Or someone is trying to sell special "CAN solder" - LOL.

  In reality, you can run CAN thru two straightend coat hangers for
  a short (few feet) distance - or untwisted ribbon cables.

  I think they are trying to scare everyone.

  CAN (for example) has been used in the internal networks of BMW's for
  many years.  The legislated use of CAN as a diagnostic layer merely
  added "one more" CAN bus to the car.  This one at 500mbps.

  FWIW, CAN was invented by Bosch specifically for use in vehicles

  http://www.semiconductors.bosch.de/pdf/can2spec.pdf

  If someone is interested, here's an appnote by Microchip.

  http://ww1.microchip.com/downloads/en/AppNotes/00228a.pdf

  If someone is REALLY interested, ISO-11898-2 specifies the physical layer.

  Generally UTP (unshielded twisted pair).

  Just be neat in your soldering and you should be fine.

  Similar to terminating a network cable try to "untwist" only the very
  minimum necessary for a repair.

  Jim