I have been conjuring up a method of making a "heads up" digital speedo and tach display to sit on the dash. I understand the Mazda mechanical speedo puts out pulses to the ECU. Can anyone tell me how many pulses per tranny output shaft rev is generated? When I get it done I'll post schematics if anyone here is interested. It would also be helpful if someone could identify the wire coming from the speedo going to the ECU that carries the pulse output.

 

the ecu gets a signal from the seedo? news to me. ...

where do you plan on getting the projector thingy? from a vette or a caddy i asume?

 

if it where me i would use a 240sx headsup display.

 

the speedo is cable driven. The tach is what is run from electronic pulses.

 

There is a speed sensor used by the cruise control. Check the factory service manual.

 

yea use the 240 one, it actually looks good with a peice of tint on the windshield for it to reflect on (i HAD an s13 )

 

I think I remember summitracing selling HUD speedo units.

 

Yes, Defi sells their VSD Basic (i'm not a fan of it). I've built a couple of them using 320x320 displays and built night-vision HUD's with speed/tach on the bottom, was damn expensive though, I think it cost us damn near $2300. For simpler things like text/etc, just get a VFD and build yourself a controller, then wire in tach inputs, speed sensor, etc. I used to install toggles on the steering wheel for call backs on max speed/rpm/whatever other sensors I was using. Was pretty cool stuff.