Re: Heads up display

[Ken Kelly <PCMdoc@surfree.com>]

Dan,
	The VSS output is analogue. It is a differential signal from a reluctor
in the tailshaft. On your car it is 40 pulses per tailshaft revolution.
The PCM scales it to the 4000 pulse per mile signal. I think the speedo
signal is 5Volts, but don't quote me.

		Ken


Dan Gentry wrote:
> 
> Again, see below.
> 
> Ken Kelly wrote:
> 
> > 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.
> >
> 
> As I read it in the manual, it's a sine wave from the sensor, then a digital signal from the
> computer to the speedo.
> Question: Is it 0V (low) and 5V (high) or 0V(low) and 12V(high)?
> 
> Question: If it's 4000 pulses per mile, then I've got the following formula to go from pulses
> per second to MPH...
> 
>     MPH = (Hz * 360) / 4000
> 
>     So
> 
>     60.003 MPH = (66.67 Hz * 3600) / 4000
> 
>     1.008 MPH = (1.12 Hz  * 3600) / 4000
> 
> Am I thinking about this correctly?
> 
> >
> > 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.
> >
> 
> That's kinda what I was thinking, but I didn't have any information on foreign car's VSS
> setups.  They asked for my make of vehicle, engine type, and year, and sent it off to their
> "Engineer" who said that it wouldn't work.  Good think I didn't waste the $190.
> 
> >
> >                 Ken
> >
> 
> Thanks, Ken.
> 
> Dan
> 
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