digital speed sensor? (gearbox/speedo question)

[RomanV]

Hi there.

I am planning on making an HUD style speedo.

My question is, how does the toyota electronic speed sensor in the gearbox output the data? (specifically, in a 1998 SW20 NA gearbox)

eg. Does a voltage increase as speed increases?
Or does it work on a 'pulse frequency' type system, where for example it would send an electrical pulse every time the wheel rotates.

Any ideas? Im going to have a play when I get home, I was just wondering if anyone had any more information on how these work.

Cheers.

[RomanV]

Or I had another idea, that I would try if I had a car to wreck.

Basically, its pulling out the whole speedo/fuel gauge/etc. assembly, and flipping it up 90 degrees and turning it around 180 degrees. You would beef up the back lights, and turn your ordinary dash cluster into an HUD on your windscreen. *ponders*
*looks at old AE92 with evil grin*

[RomanV]

I just had an even better idea. I could use my alarm clock as the housing for my digital speedo. The 'clock' display can be the speedo and/or rev counter. The little night light can be used as a shift light, and I could hook up the buzzer to let you know when you are going over 110kph. Hehe, that would look pretty sweet.
You could also use the buttons on the top for different things, eg. You hold down one of the buttons and it displays your oil pressure, or coolant temperature, or whatever.
It would be a high tech, ghetto looking display system.

[Mr Revhead]

lay off the pills dude

[slighty_sykotic]

Pmsl, thats a great thread start

Umm, pretty sure thats its a pulse system, more pulses as speed increases. Chuck in a analog multimeter, will tell you if its pulsing or not.

--Sykotic