Anybody know how ecu percieves engine speed? (I'm trying to make a tachomter)

[henryc]

My friend has a 1990 Corolla, (with the smallest engine available in 1990). The car has few, if any, options and so it does not have a tachometer.

I am trying to put together a little program on a microcontroller to translate the digital signal going to the ecu into either a pattern of LEDs or possibly even a digital display.

However, not owning a Corolla myself, I have no service manual or any related thing, so I was wondering if anybody on here knew what format the ECU receives its engine speed information in? I assume it is a certain number of pulses over a certain amount of time, but I do not know what. Anybody know anything? I'll give you a LED tachometer in return. :P

-- Henry

[Chris Corolla S]

moved to tech section...

[jm_2thow]

http://www.toyotanation.com/showthre...threadid=23727

look down on the first page i think, theres a guy that makes a tach out of some led lights at 500 rpm intervals. tells u how to do it and everything