2003 Grand AM Tachometer Wire

I am trying to install an Astrostart in my wife's 2003 Grand AM and I am having trouble finding the Tachometer wire. it has the Ecotech 2.2 engine. I have the instructions for the V6 but it says the white wire and when I connect to that wire on the top of the motor or any other wire in that connector on top of the motor I get an error code on the Astrostart that says no tach reading????