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Re: Heads up display
Dan,
Just a couple of comments.
1) The 16188051 in your camaro puts out 4000 pulses per mile for your
speedo. It is not a sign wave. It is a digital pulse.
2) Something is wrong with your info on the japanese HUD display. It
could not work with 2 pulses per mile. How could it possible integrate
things well enough to put out a speedometer reading. At 10 miles per
hour, it would only get 20 pulses per hour! Maybe it is pulses per
speedometer cable revoloution in the Mechanical speedometer
applications. Mechanical speedometer use 1000 revolutions per mile, so
the 4 pulse per revolution would be 4000 pulses per mile.
Ken
Dan Gentry wrote:
>
> Um, whoops. See below.
>
> Peter Gargano wrote:
>
> > Did you have a message hidden somewhere within the ">" quotes?
>
> 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 and 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.)
> 4: Use an in-car computer (my MP3 player) to talk to the ALDL and get the data from
> there, driving a display.
>
> What do you think?
>
> Dan
>
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