On Mon, 7 Dec 1998, Ed Garbacz wrote:
> Since those of us with the 97+ Daks cannot easily pull the codes using
> the on/off key method does any one know if it would be possible to rig up
> a cable that would attach to a laptop computer that had some custom software
> that could read the codes? I would be willing to write the software if
> someone knew the format of the data that is used. I'm not sure it would be
> possible but if anyone knows something about it please let me know.
>
Absolutely. There are a few such products that already exist, from
CompuCar and EASE Simulations. (www.compucar.com and www.easesim.com)
They are in the $250-300 range, though some of them do much more than
read DTCs.
I have been looking for the data format myself. What I was planning
to do was create a little handheld device with a microprocessor for a brain
that would plug into the OBD-II port, read the DTCs, and spit them back.
(maybe even with an option to clear them) Something like that could probably
be built by the average person and the parts should be relatively cheap.
The OBD-II port is just a serial connection, so it should be fairly
easy to whip something up. Unfortunately, I don't know any of the
connection details (baud, etc) nor do I know the underlying protocol.
The connector itself is an SAE J1962. I've got the EASE software
and cable, there are only a few pins actually being used. If you
like, I can take a look at the cable and tell you which ones...
I do know that there are 3 OBD-II protocols, ISO, PWM, and VPW.
All Chrysler products, including our Dakotas, use the ISO protocol.
(ISO 9141-2) I have read that this connection is 10.4kBaud, but I
can't confirm that.
I'm assuming that the details of this protocol are available somewhere
(probably for a fee) but as of yet, I've been unable to find any details.
I'll definitely let you know if I come across anything though. Likewise,
if you find something could you let me know?
A good place to check might be http://www.obdii.com. Click on
"other links"; there is a section there of SAE reference publication
sources, and they'll take you to various places on SAE's web site
where you can order these documents. Unfortunately, the descriptions
of the various documents are vague, and I'm not sure that they
contain what we're looking for, or which one to order. They're expensive
enough that I don't want to just guess... ($40-80) I suppose I could
just write SAE and ask 'em which book to get...
-Jon-
.--- stei0302@cs.fredonia.edu ----------------------------------------.
| Jon Steiger * AOPA, DoD, EAA, MP Race Team, NMA, SPA, USUA * RP-SEL |
| '96 Dodge Dakota v8 SLT CC (14.58@93.55), '96 Kolb FireFly 447 |
`--------------------------- http://www.cs.fredonia.edu/~stei0302/ ---'
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