Diacom cable for GM

[Terryk]

The red wire is connected to +12V only if the CE light is burned out. It is
not needed on serial (PIN M) ALDL connectors. It just replaces the pullup
that the CE light provided.



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> From: sfg <sfgent at ac.net>
> To: diy_efi at coulomb.eng.ohio-state.edu
> Subject: Re: Diacom cable for GM
> Date: Monday, October 13, 1997 5:40 PM
> 
> swagaero wrote:
> > 
> > sfg wrote:
> > >
> > > I purchased the Diacom diagnostic interface (GM) kit back in '92. It
> > > runs under DOS and has been worth the $200 or so I spent on it.
> > > The supplied cable, which connects your RS232 to the ECU (ALDL) has a
> > > red wire for 12VDC input. Recently I discovered the system works
with,
> > > or without the 12VDC connected. I had always assumed there were
active
> > > components molded into one of the connectors; now I am wondering if
its
> > > really just a hunk of wire, with connectors on each end. Anyone know?
> > > Steve
> > 
> > diodes, diodes, diodes, diodes and more of them used as gates and most
> > ECM's don't neeed the voltage
> > 
> > Steve Parkman
> > --
> > 
> >                    ----|------||------|----
> >                      --|------[]------|--
> >                             0/  \0
> > 
> > :http://www.flash.net/~swagaero
> 
> Steve, please elaborate a bit. If you are familiar
> with this interface cable please, enlighten us. When I first saw the
> +12VDC wire, I followed the Diacom instructions to connect it. Later I
> found by accident that it wasn't reqd. (initial assumption being that
> there was logic-level conversion or inversion going on, or pull-ups
> required, and ICs were potted in the connector shell...too much to
> expect GM to provide RS232 right at the ALDL) Are all output
> pins on the GM ECU open collector? Is there a FAQ on this which I 
> missed in the archives (I've looked).
> Whats the scoop?  
> Steve Gent    "well built 383 SBC seeks hot TBI for fun & torque" .....