Re: Heads up display

[Dan Gentry <dang@seanet.com>]

> Dave:
>
> Thanks for the data - please see below for more.
>
> Dave Hempstead wrote:
>
> > Hi Dan,
> >    Well I can tell you what I know about HUD's and PCM's.  In your 95
> > Z28, your PCM has software in it for a HUD.  It collects lots of data
> > from its sensors, and sends it to some HUD hardware.
>
> Right.  I don't know if it's a question of having HUD-specific software in the
> ECM or not though.
>
> >
> >     Now, never having seen the HUD or the hardware driving it, I can't
> > tell you how to hook it up, but it sounds like you have some ideas
> > there.
>
> Yup - I've been lucky enough to find two "friendly" auto dealers here in the
> Seattle area that were kind enough to let me leaf through service manuals and
> get photocopies of some rather important data.
>
> >
> >     Also, I BELIEVE that you may need to set a bit or two inside the PCM
> > to enable the HUD.  I'm not sure here, because I haven't studied the HUD
> > code in that much detail (usually I just skip right past it), but I'm
> > not sure if it is always enabled, or if it is enabled by plugging in the
> > HUD hardware.
>
> Oooh, I didn't know that.  Interesting.
>
> >
> >    Having said all of this, I am now wondering if we are talking about
> > the same HUD's or not.  It is my understanding that the 94/95 PCM's
> > drive a HUD for GM's test purposes.  However, maybe the HUD is one and
> > the same.
> >
> >    Maybe you can enlighten us on what HUD's you know about, and what
> > they are available on.
> >
>
> Okay - here goes.
>
> I know for sure that 1999 & 2000 Corvettes and (at least) 1994->2000 Grand Prix
> models have the Heads-Up Display as an option.
>
> I'm casually aware, but not sure in any detail that other GM models have HUDs
> (Olds, Buick, etc).
>
> GM's HUDs are made by Delco Electronics (naturally!), and have the trade name of
> "Eye-Cue".
>
> GM Vehicles equipped with HUDs have a special windshield that is a sandwich of
> different materials to make the HUD image clearer.  I'm assuming that the
> special quality of the material (referred to as PVB in Delco's literature) is
> some kind of polarizing filter.
>
> The HUD units that I've been able to read about in service manuals are single
> enclosed units with display, optics, and adjustment motors enclosed in a "neat,
> tidy" package.
>
> I do not know if there is enough space behind a Camaro dash to install a Vette
> or GP HUD.  Some mods would certainly be required.
>
> The part number of the HUD on 1994-1996 Grand Prix models is 16141842.  HUDs
> from this era that are defective are sent to a third party (Instrument Sales and
> Service here in Seattle, and others across the country).  They will not sell a
> HUD without an defective exchange.  (Darn!)
>
> The GP HUD shows Speed, Turn Signals, and other idiot lights.  It gets speed
> data from the PCM at the rate of 4000 pulses per mile.  The PCM gets it's data
> from the Vehicle Speed Sensor.   The manual states that the output of the VSS is
> a sine wave.  I'm assuming that once the analog output of the VSS hits the
> computer it gets converted to something a little more TTL.  The output from
> there goes to the instrument cluster.  BTW: Does anyone know the specifics of
> this signal so I don't have to go buy an o-scope to figure it out?!
>
> The 'Vette HUD seems to be a much more advanced unit.  The Vette service manuals
> don't have nearly the same level of wiring detail as early books do - I'm
> assuming that there is a computer program that displays detailed diagrams in the
> repair bay.  The HUD unit itself costs $992 (as quoted by the Chevy dealer) -
> OUCH!  The wiring harness for the HUD looked like it plugged into the back of
> the speedo cluster, but I can't tell.
>
> There is a Japanese company (http://www.defi-shop.com) that sells an add-on HUD
> which uses a polarized window film and sits on top of the dash.  I was going to
> purchase one, but the information states (in the docs on the site) that the
> input speed pulse must be 2, 4, 6, 8, or 16 pulses per mile.
>
> Knowing that my Camaro (along with Grand Prix and Vettes) puts out 4000 pulses
> per mile, I didn't order it.
>
> There - now you know as much as I do about the subject.  Not much, is it?!
>
> Here's how I'm thinking about proceeding:
>
> 1: Try to develop a circuit ( Basic Stamp?) that will divide the VSS pulse by
> 1000 and purchase the Japanese HUD.
> 2: Try to develop a whole HUD myself (again, Basic Stamp).  Use the VSS and Tach
> inputs.
> 3: Continue to pursue the option of finding a "used" HUD from a Junkyard. (No
> luck so far.)
>
> What do you think?
>
> Dan

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