I have yet to get the tach to work at all since the LS engine swap in my '89 Firebird. It would be helpful if somebody could verify I am using the correct connection.

I have Holley HP EFI and have verified with an O-scope that there is a tachometer signal with a square wave at system voltage. I am running that signal through C100 D6 terminal (white wire). And I have verified the wire goes to the BROWN connector Pin 1 at the gauge panel, as shown below. The circuit trace from Pin 1 winds over to a connection at the tachometer with a negative symbol close by.

Is there anything wrong with the connection itself? Am I missing a screw in the empty hole next to the negative symbol? If not, then I suspect the tachometer to need repair.

 

Well damn, this guy has a screw that I am missing.

http://s35.photobucket.com/user/Cree...e0020.jpg.html

 

Yep, that was it. Tach works now and it is really accurate too.