Modifying OBD-II systems

[Donald Whisnant]

>Date: Wed, 12 May 1999 10:55:12 -0400
>From: Bill Shaw <bshaw at connix.com>
>Subject: Modifying OBD-II systems
>
>Hi,
>
>As I understand it,  OBD-II is more difficult to hack then the pre-OBD-II
>systems.  Has anyone on the list worked around the security and
>successfully hacked their OBD-II system?  What problems did you have in
>doing so?  Did you need any special equipment? I'd love to hear any OBD-II
>success stories.
>
>Thanks,
>Bill
>

Bill,

No, OBD-II systems in many ways are actually easier than their OBD-I
counter-parts...  The goal of OBD-II isn't to make it more difficult to
tune, modify, or monitor, instead, the goal is to actually (in many
ways) make it easier -- making it more standard across different
manufacturers...  There is an increase in device [sensor] performance and
functionality monitoring within the OBD-II PCM's and this is where the
common misconception comes about...  This enhanced monitoring of
sensors has caused problems for people who do aftermarket changes,
since it may set trouble codes...

What this means is that for even simple changes and modifications, it
may be necessary to do either tuning changes in the PCM or change the
"error detection" ranges within the PCM...  However, it is good to
do this tighter, more strengent testing, because you can detect problems
quicker and track them easier to their source...

Unfortunately, I can't give any details about how to hack, modify,
or otherwise change OBD-II computers, because of my job...  But I can
rank the difficulty level...  On a scale of 1 to 10 with 1 being stupidy
simple and 10 being practically impossible, I'd give it about a 3...

Good luck with it...
Donald