AC Delco ECM

[FIScot at aol.com]

In a message dated 96-06-26 17:09:37 EDT, Martin Scarr wrote:

> have a complete EFI setup from a 2.8 V-6 out of a '85 Firebird.   I 
>plan on using a Hobbs switch to enrich the mixture under boost.  I have 
>good fabricating skills and a shop to make the manifold adapters as needed.

Personally, I would get rid of the 85 C3 ECM with it's slow ALDL, and use the
1227730 P4 ECM (with fast ALDL) used with the 87 and up 2.8's. The 1227730's
are plentiful, because GM used it in a lot of applications, and all the code
is in the EPROM. I bought an '86 'W' engine ECM (for the 2.8) and that is
probably the same ECM you now have.  After coaxing the code out of the ROM on
the board of that C3 ECM, it turns out it has no knock sensor handling in it.
You need (or at least should use) knock sensor handling on your
turbo-equipped Corvair.  You could put a knock sensor on each head.....
 

>How is the code physically extracted from the ECM?  I mean where do you 
>attach, at the ribbon cable going to the sub board?  Where do you get 
>disassembler software to look at the code?

You need to halt the ECM's processor,  force an external address to the
address bus and then read the data on the data bus.  I did this with a
bi-directional printer port and a CD4040 counter.  You could probably use a
PROM burner if you were creative. (Just remember  not to connect the
programming voltage!) The complete address and data bus is available on the
edge card connector on one of the ECM boards.

I know of no available 6801 disassemblers.  I got a programmer at work to
help me making a crude 6801 disassembler.  It does the job, but requires some
manual tweaking to get the resulting code right.  I guess I need to fix
it......

Scot Sealander   FIScot at aol.com