where can I get a tach signal to tap in order to install a shift light or a window switch? behind the tach gage or at the computer?

 

I'm interested in this info as well. I can't see the stupid shift light right now and need to add a light asap.

 

Only place you can tap is at the actual ignition coils. The computer sends the tach signal to the speedo/tach cluster via a communications channel, so there are mutiple signals transfered over this one line at various frequencies. No way you'll tap into it and find anything useful. My MSD window switch is hooked directly to the wire from the ECU to the iginition coil packs (any one of the 6 will work fine).

Dan