Help needed reading Ford EEC-IV data stream

[Donald Whisnant]

At 01:40 PM 11/23/95 EST, you wrote:
>
>
>I have a 1984 Riviera (probably similar to your Grand Prix) and also
>thought that it did not have a serial data pin and only stored error codes.
>However, I took the car to a mechanic friend of mine who hooked a scan
>tool (OTC I think) to the ALDL connector and was able to read the TPS
>voltage on the display!

You are right --- After further research, I've found indications that it
does transmit data...

>I would love to know how this is done and perhaps build a PC interface, I
>got a lead from auto.tech newsgroup about a device called device called
>AutoXray,  contacted one Bill Miller (wjm at goodnet.com) who apparerntly
>works there and asked him how you get data out of thesee cars, this was his
>reply:
>
>  Lloyd:
>  In order to monitor data from a General Motors Car,  It is necessary to
>  enter into an agreement with GM to get the data and protocol by which the
>  card communicates.  Once that is accomplished There is much product
>  development work.  The AutoXray XP240 should serve your purposes well
>  because of its ease of use and affordability.
>
>I phoned them for an information package on there product but so far no
>reply (almost a month).

I just received a flyer in the mail today from them that I requested last
week ... And the flyer did mention the ALDL montoring capabilites --- I'd
give you the prices but I left the letter up in Salisbury (about 45 minutes
from here)...  I'll post the prices that they listed tomorrow when I 
retrieve the letter.  .... Obviously the person you spoke with at AutoXray
just wanted to sell his unit without giving out any info --  What we should
do is get one of the units, examine it with a scope and logic analyzer, and
then build our own unit to market -- if for no reason other than defiance...

>If anybody knows how this data is extracted please let me know, just for my
>peace of mind.

I haven't spent much time on the older ALDL system since all of my current
needs now are OBDII type... Hopefully I will soon figure it out and build
an interface for it...  But If I come across something else on the ALDL, I'll
send it your way...

Donald Whisnant
dewhisna at ix.netcom.com