Rev liminter help

[Caterman7]

I could use a little guidance here as my electrical knowledge is just enough to get me in trouble. I purchased a Pertronix Digital Rev Limiter to install on my 96 Caterham. Most of the wiring is pretty basic - positive and negative to the coil and a ground wire. The last wire is the one I am unsure of and have gotten conflicting answers on. It is listed as "tachometer output". I've been told it goes to the alternator (but not where) or to tie into the center of the three wires on the back of the VDO tach. Two dissimilar answers requires me to contact you guys for help. On second thought I should have posted here to begin with :willy_nilly:. Thanks in advance for any input.

 

I posted this first under general discussion, sorry.

[MHKflyer52]

Check your first post for some helpfull info.

I have made the same mistake so don't feel bad.