> Date: Mon, 7 Dec 1998 15:01:17 -0500 (EST)
> From: Jon Steiger <stei0302@cs.fredonia.edu>
> Subject: Re: DML: Check engine light
>
> 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/ ---'
>
> ------------------------------
Jon,
Thanks for the info. I will check out the sites that you suggested.
I was hoping that it was a simple serial port conection that will make
things easier. I like your idea of a handheld device, I was thinking along
the same lines except instead of a custom built piece of hardware I was going
to use the 3Com PalmPilot. It is a handheld electronic organizer that has a
serial port and it can be programmed to do just about anything. I will keep
you up to date on anything I find out.
Ed G.
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