GM P3/P4 ECU scan tool's

[steve ravet]

Stuart Bunning wrote:
> 
> Hi all
> 
> I am new to this list so please excuse me if this question has been asked
> several times before.

I wish I had a dollar for every time I've seen this post either here or
on 
usenet...  :-)

> 
> Is there any SHAREWARE/FREEWARE scan tools that allow me to monitor the GM
> ECU via a laptop. I am aware of DIACOM and tech 1 and other scan tools but
> they cost a bit. Before I spend hard earned cash I would like to check first.

Ken Mosher has a product called TurboLink.  Very good, but only for
Buick GN/Ttypes.  I understand it works OK on on similar cars.  Not a
general purpose scan tool at all.

That's the only thing I'm aware of besides Tech 1, OTC, Diacom, etc.

> 
> I am currently trying to decode the ALDL streaming data that runs at 160
> baud or 8192 baud depending on what model ECU is being used I have nearly
> worked it out but still have a long way to go. Has anyone got or more to the
> point willing to give information on this protocol . Is there any shareware
> available?? If I am successful in writing a scan tool I would like to offer
> it at no cost to all.

First, have a look in the archives.  Lots of good information in there,
including the electrical encoding of the 160 baud stream. 
Unfortunately, the hard part isn't there, what the bits and bytes in the
stream mean.  I've been in contact with a Delco engineer, according to
him it varies by model/year/powertrain.

The best way to figure out ALDL is to get a scan tool, and either
eavesdrop on what happens using a PC, or hook your PC right to it and
send frames, varying the info and seeing what changes the scan tool
reports.  Unfortunately that costs money, which is probably why no-one's
done it...

--steve


--
Steve Ravet
International Meta Systems
http://www.imes.com
steve at imes.com