ALDL summary and thanks for participation

[FIScot at aol.com]

    Subj:   ALDL summary and thanks for participation
    Date:   96-01-26 13:23:53 EST
    From:   gmd at tecinfo.com (george dailey)


  > There are some hardware goodies in the Diacom software cable.  The
  > goodies may have been placed there as a marketing protection device.
  > Think about it.  Diacom sends signal to goodies, goodies respond back
  > to Diacom, Diacom will now start reading the ecm data.  This kills
  > software pirating.  Or they may be legitimate hardware interfaces.  I'd
  > like to know what our expert readers have to say.

    I don't care one way or the other.  I spent the 300 bucks and have no
    regrets.  Buy it and enjoy it.  You will never figure out so many
    vehicles.


  > The pre P4 ecms will transmit on demand at 160 baud.

    Most are transmitting all the time anyway.  Don't try and apply hard
    and fast rules where the are just not there. Most P4s are 8192 only.


  > "The ALDL for my (Dan Fugerson) 89 Suburban is a continuous 160 bit/sec
  > bit stream.  It begins with a sync character of 9 consecutive "1" s.
  > Each subsequent byte begins with a "0" and then the 8 data bits.  The
  > stream continues until all data is read.  Another sync character is
  > sent and the stream repeats with updated values."

   This is good info.  Believe it or not, this is all done in software.


  > The P4 and later ecms have to RECEIVE a pass data stream before they
  > will transmit at one of two predictable baud rates.  160 or 8192.

    The P4 you are refering to is the 86-89 Camaro ECM.  This can transmit
    at both rates, but it may be the ONLY ECM that does.  It will transmit
    at 160 with no external prodding.  The 8192 data stream with all the
    good data will not transmit without the correct outside prodding.  The
    rate is not determined by the 8192 data sent to it.  It responds to
    8192 data it was sent with 8192 rate data.


  > "The data is not in ASCII, but regular 8-bit (mostly) unsigned
  > integers.  There are some 16-bit values that come out.", Scot
  > Sealander.  Scott, I plan to RTM, in the mean time, can you feed us
  > folks in hacker land a few more tidbits of information that you think
  > would help a hacker.

    A few years ago I was in the same boat.  It takes alot of effort, but
    it can be done.  I have no affiliation with GM, or any other
    organization dealing with ECMs.  This is hacker knowledge....  RTM.


  > If the data string is unsigned integers for new or old ecms, the hacker
  > would have to convert each integer to it's real number equivalent.
  > Some of the data is in the form of "A/C yes" Once you got the real
  > numbers you must decide which physical parameter it stood for.  Time
  > consuming but not impossible.

   Can you say data byte?  Can you say status byte?


 >  OBD-II standards:  I'm sure this is an excellent standard but, I know
 >  nothing about it.  ouch!

    Me either...  I hate it when the feds get involved.

 >  Bottom line-- I've got a complete 350 '89 TPI harness on my living room
 >  floor.  If I can get some code to read the raw data, I'll tinker with
 >  converting it into usable data.  As soon as the weather breaks, I will
 >  put the whole TPI setup in Maxine (my chopped and dropped '58 Chevy
 >  truck) and cruise for women!

    Out to get more trouble?  ;-)

    Scot Sealander   FIScot at aol.com