Accessing GM Serial Data

[Philip Logan]

Hi, I've just found this mailing list in the last few days and would have 
lurked for a while, but this thread is one of the main reasons I sought 
out a DIY_EFI type of list. 

I've got an '85 Fiero, and I'm interested in accessing the serial data 
stream, but so far I haven't tracked down any specification. Looks like 
the knowledge exists in this forum. Is there a FAQ with this info ? 
The Fiero ECM is common to the Celebrity etc. and is the same as the 
subject of the Email that's quoted here.

I want to use the serial data stream in a dash computer whic also gives 
access to the engine diagnostics, so purchasing off-the-shelf isn't an 
option.

My other interesting car is a Mazda Miata, which would benefit from the 
the addition of a knock sensor/timing retard unit, especially when the 
turbo goes in :-)

Hope this query isn't one of those RTFM or rather RTFFaq queries.


> >>The connector in my car seems to match this description.

ditto

> >>One of the readers sent me some interesting information of the GM serial
> >>data communications protocol which seems to run at 160 baud and says that it
> >>is a continuous data stream. Another reader has explained the format of the
> >>data, 

I'd appreciate a forwarded copy of this info.

best regards from a new reader,

Phil Logan
Blue '92 Mazda Miata (manual)
Red  '85 Pontiac Fiero 2M4 Sport Coupe (auto)
Tan  '88 Hyundai Excel (manual)
Highland Park, NJ