Really? Do you have a link? I can't find one.tongtoy:
you can buy a 35 dollar converter on ebay and plug it in - works off of a tach signal from the car expecting a coil or an rpm sensor from a crank wheel of some kind
i'll pull the name off of the one I have in the jetta. It was an ebay purchase two years ago I guess now a days.e*clipse said:Really? Do you have a link? I can't find one.
I've found Dakota ones for $60 - $100 and a used splitter for $31, but nothing as versitile or easy to use as the one I'm developing.
For example: Say you put 33" tires on your truck that originally came with 31's. Could you calibrate your speedometer with one of these inexpensive adapters?
good info ^^ for vanagon users and may also work for toyota?Hi,
I converted my T3 syncro (vanagon) to TDI (AFN code engine).
I tried to use the tacho output of the TDI ecu (pin 2/68), but factory tachometer of the T3 (gas engine) did not work.
I took the tacho out and examined, yes there are resistors (a voltage divider) on input signal.
The chip used in the tacho is SAK215, it is a frequency to current converter. I found the data sheet of SAK215 (googled it) and it says anything between -20 to +20 V is valid as an input signal.
As the TDI output signal is a 0-12V square wave, I just directly conected it to input pin of SAK215 (bypassing all the filters and resistors in tacho), and it worked.
It is accurate as expected!
Well then. I cave. I have another unmolested tach and rather than modify it (perhaps unsuccessfully again) I purchased the needed bits from Rock Auto. If it ever stops raining raining here I will post back with photographic results.check out my solution for a tach driver using an inductive pickup...super simple....about the third post down starting...if you wanted to do this using a V6 tach you could weld three nuts 120' apart....
The tach is reading frequency from the W terminal, not voltage, so a resistor won't work unfortunately.Hi guys, i have a 90spec 8v gti with a mk3 ahu engine in. Ive installed the correct mk2 gtd clocks with the rev counter and reading from the W pin. It reads about 400rpm too much at idle and at a guess about 700rpm at 70. Ive seen a couple of how to's etc im wondering what is everyone elses solution to having an accurate rpm dial? Can i place a resistor on the W PIN WIRE?
The tach is reading frequency from the W terminal, not voltage, so a resistor won't work unfortunately.
Sounds like your tach is a bit out of calibration for your particular alternator pulley/crank pulley ratio... if I recall correctly the MK2 clocks have a couple of calibration pots on the back of the circuit board.
A little googleing might track them down.... you could also try posting over at www.vwdiesel.net... lots of folks there have done conversions and there are several detailed tach threads.