Vette serial data and scan tool communications

[Shannen Durphey]

Well, I've got a 91 Vette torn apart at work.  And I thought I'd check
to see if the ecm will communicate with a scantool if the CCM is
disconnected.  So I pulled out our Snap-on scanner, plugged it into
the ALDL (or DLC if you like that term), and tried to talk to a 91
Corvette.  The scan tool wouldn't display a word.  But knowing that
the same ecm used in the L98 Vette is also used in cars with no CCM, I
started selecting different model cars.  First choice was a 91 F body,
and that was as far as I needed to go. The scan tool linked right up. 
Al had also mentioned this the other day.  I also started the car and
checked for codes.  The CCM, ABS, instrument cluster, HVAC programmer,
SIR DERM, and stereo were disconnected and the ecm did not know or
care.  The car started and ran fine, and set no codes.  

This isn't an exact test because it's not the same ecm as what's been
discussed the last few days.  But for anyone looking for encouraging
information, this would be it.
Shannen