GM 2.8L V6 ALDL

[Shawn R. Lin]

Bill Shaw wrote:
> 
> This sounds real similar to the '749 ALDL.  You might find the description of the '749 communications in Turbo_P4_Doc.pdf  in incoming helpful.
> 

Thanks, that's a very informative doc!
I FINALLY got some Mode 1 data in Carbytes v2.0.
The most important thing I had to do was check "Echoed" to tell Carbytes
that my MAX232 interface is echoing everything sent to it.  I also
decreased "ALDL Wait" to 2ms, not sure if that helped anything or not. 
It seemed to make it easier to get into Mode 1 the first time, but I
could be mistaken.
I sent the ECM "F0 56 01 B9" about 4 dozen times, finally I received one
LONG string beginning with "F0 95" - the correct Mode 1 return string.
If I send another F0 56 01 B9, I can get another Mode 1 string
returned.  I can keep doing this reliably as long as the ECM remains in
Mode 1.  I have to send successive Mode 1 requests within 5 seconds of
the last one or else the ECM drops back into Mode 0.  When that happens,
I have to send Mode 1 requests another 4 dozen times just to get back
into Mode 1.

So now what I wonder is, how can I get a program like Carbytes v2.0 to
repeatedly send Mode 1 requests?  I'd like to make a Mode 1 definition
for Carbytes for my car.

Shawn



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