tach help
The easiest place to find (and get to) is going to be the ECU wiring harness.. The wire also runs under the dash into the instrument cluster, but unless you can trace it, It may not be easy to find.
On the ECU, it's the crank position sensor which is pin 89 in the diagram below.
http://www.roadraceengineering.com/e...-ecuwiring.htm
http://www.roadraceengineering.com/e...-ecuwiring.htm