Diacom cable for GM

[John Hess]

actually, if memory serves me right,  it is a transistor/resistor array,
not diodes!


> ----------
> From: 	swagaero[SMTP:swagaero at flash.net]
> Sent: 	Monday, October 13, 1997 9:16 PM
> To: 	diy_efi at coulomb.eng.ohio-state.edu
> Subject: 	Re: Diacom cable for GM
> 
> sfg wrote:
> > 
> > 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
> > > --
> > >
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> > >
> > > :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"
> .....
> 
> 
> No IC'S in the potting Yes I took it all off only took 3 hrs. Just
> some
> fast diodes for switching. only one line returns to ecm the rest are
> level signals out. I didn't go any further as I could not write
> correctly back which is what I wanted to do. I will have to see if I
> can
> find it and take a look at it. It's been several years. I am using the
> GM/veiwtronics tech 1A to do the writing to eeproms now. Just rewrite
> the programming cart and rewrite the eprom. Yes I know it's a little
> pricey but it's the only way to get to the GM eeproms.
> 
> Steve
> -- 
> 
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>                      --|------[]------|--
>                             0/  \0
> 
> 
> 
> :http://www.flash.net/~swagaero
>