Kevin,

You won't get a response in a tach designed for a gas engine. You do;t have
an ignition to pickup anything from in your diesel. You need to pickup the
RPM's from the alternator or some other rotating part. You will need some
sort of interface to translate revolutions into some sort of impulses that a
compatible tach can read.

Here's one way to go:

http://www.cs.rochester.edu/u/jag/vw/engine/tachometer.html

Or go the easy route that Michael Sullivan turned me on to at Dakota Digital:

http://www.dakotadigital.com/products/tachadapt.htm

BenT
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