OBD_II You asked for experiences

[David A. Cooley]

At 10:11 PM 5/13/99 -0400, you wrote:
>> I then spent the next couple of days at the standards
>>office going through
>>the data I had gathered, I found that the first thing the diag tool did was
>> request that
>>the ECU unlock, to this the ECU responds with a two byte seed value, the
>>diag tool then responds
>>with the correct key for this seed value and the ECU is unlocked.
>
>
>For the American cars, the vehicle serial # is programed in to the ECU.  The 
>ECU also has it's own (different) serial # printed on the outside.   I wonder 
>if the serial # laters the code.

The SAE J-1850 spec states that the manufacturer can use whatever security
algorithym they want... IE it's not a standard code formula.
The protocol for the communications is a standard, as are the trouble
codes... the rest is up to the maker as to how they want it.
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           David Cooley N5XMT           Internet: N5XMT at bellsouth.net
     Packet: N5XMT at KQ4LO.#INT.NC.USA.NA   T.A.P.R. Member #7068
   Sponges grow in the ocean... Wonder how deep it would be if they didn't?!
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