Help needed reading Ford EEC-IV data stream

[Donald Whisnant]

At 06:15 PM 11/22/95 -0500, you wrote:
>
>I'd like to write a program to tap into the data stream, via the
>diagnostic connector, on my 1993 Ford Escort with its 1.9 liter
>engine.  If the data stream consists of standard RS232 signals,
>I might be able to use a datascope as the first step in writing
>a BASIC program.  This program would read (not write) the data
>stream via a laptop's standard serial port.

I'm doing something similar with my 95 firebird and 85->93 Grand Prix (if
you're wondering about the 85->93 part, it is an 85 car with a 93 engine)...
First off... I can guarantee you it is not a "standard" serial data
stream --- (if you can call anything "standard") ... most databooks indicate
a "non-standard" baud rate... plus, all handshaking is very different from
RS-232 as well as the data structure --- probably an interface between the
port and the computer will be required ... I've recently ordered the SAE
HS3000 document that covers what GM is doing, but I haven't got it yet so
I don't know if it covers Ford or not [someone else out there may know -- like
Dan Burk]

>Diacom is a product of Rinda Technologies in Chicago that uses the
>parallel port of a PC to extract much information from the ALDL
>connector of GM cars and from the corresponding connector (don't
>know its name) of Chrysler cars.  They told me that pre-OBD-II
>Fords, such as my EEC-IV Escort, don't have much information beyond
>stored error codes available at the diagnostic connector. 
>
>I know that a Snap-on Model MT2500 scanner hooks into the Escort's
>diagnostic connector and displays data -- definitely beyond stored
>error codes -- on its 4-line screen.  I'd like to write BASIC
>programs for a PC that read the signals coming from the connector,
>save them, and reformat them for display.

It could be that error codes are all that it stores -- kinda like
my 85 Grand Prix used to do (it used to not have a serial data pin on the 
ALDL connector)  ...  I've priced the Diacom and think it is a little
high --- So I'm gonna try to build my own version (at least I'll learn
something in the process -- that should be worth something)... ...
It could be that Diacom just doesn't interface to the Ford EEC-IV and they
are just telling you that it only stores error codes. ...  Do you have a
shop manual for the car?  And, does it show a "serial data" pin --- if
so, it should be able to communicate some how to a pc...

>Any suggestions about how to get started?  For example, if I knew
>the structure of the signals (1200 baud, odd parity, etc.), then
>constructing BASIC statements to read this data stream through a
>standard PC serial port should be straightforward.  There are
>six pins in the Escort's connector plus a seventh wire.  How would
>I connect a cable from what pins of a DB-9 serial port connector
>to what seven wires at the Escort's connector?

It's not going to be a simple straight forward hookup -- you'll have to have
some interface between the two...  I seem to recall, though, that one of
the baud rates used is 10200 --- I believe that is what Motorola mentioned
in reference to one of the car ECM/PCM applications specs. ... I'll know
more about it after I get the SAE specs that I've ordered.

>BTW modern cars come and go, but a 1940 Ford coupe with a flathead
>V-8 engine has been the real car in my life for the past 19 years
>and in the future.  It was a a genuine learning experience to convert
>the distributor from breaker points/condenser to optical pickup/
>electronic coil control while keeping the 6-volt positive-ground
>electrical system intact.
>
>Many thanks for your help.
>
>Marll McDonald   KB1AGM
>m_mcdonald at marx.enet.dec.com
>
>

Good luck with the interface...

Donald Whisnant
dewhisna at ix.netcom.com