Diacom cable for GM

swagaero swagaero at flash.net
Tue Oct 14 02:14:52 GMT 1997


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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> >                             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" .....


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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:http://www.flash.net/~swagaero



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