So I have been stripping the harness down to the bare bones, and because the AEM Manual said this was an Available Output, I went ahead and removed it. Well this caused the Tach to not work. After a few hours of tracing everything back this what the only pin I could find that had been removed and related to the Tach.

So bottom line, if you strip your harness and want your tach to work, keep this one.

This is for an Evo 8 on a Series 1 30-1313

 

Good call boz!