GM's ALDL info

[Jonathan R. Lusky]

In article <1992Jan5.200542.2617 at bnlux1.bnl.gov> polychron at bnldag.ags.bnl.gov  (Ven Polychronakos) writes:
>Thanks for posting this information. I had figured out (the hard way)
>the basic protocol but had (and still do) trouble interpreting what
>I was reading. At least now I can stop trying to decipher the checksums
>and device codes.  So here is my minor, I'm afraid, contribution
>towards solving the puzzle. Below is a record of what the serial link
>on my '88 Celebrity (2.8L, v6,VIN W engine)  tells me.  Car at "PARK",
>engine idling. All digits hexadecimal.

Other values that the ECM sends back include manifold air temp and pressure,
spark advance, rpm, throttle position, as well as several fuel injection
related numbers (block learn multiplier is the only one that comes tomind at the
moment).  You might try finding someone with some type of scan tool so you
know what values you are looking for.  RPM, TPS, and MAP you should be able
to pick out pretty easy.  RPM will vary with rpm, TPS will vary with throttle
position (even when engine isnot running), MAP will vary with vacuum (even
when engine is not running... get an "assistant" to suck on a vacuum line
connected to the MAPsensor while you sample packets).
 Jon Lusky
 lusky at gnu.ai.mit.edu

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