Nissan Repair: 2000 or 2001nissan sentra, nissan sentra, coil pack

Question
i bought an aftermarket tachometer and dont know were to find the negitive wire off the coils or electronic ignition i looked at the coil pack on top off the plugs and thought o connected it to the center wire which had a g stamped on it but didnt work please help thank you 2000 or 2001 nissan sentra 4cyl

Answer
You hook it to the tach wire off the coil.  You have a ground for your tach and make sure it is connected and then probe the other two wires with a hand held tach and you will find which is sending signal.  The other option is to get into the dash and tie into the tach circuit that connects to the instrument panel.  That would be the easy way since you do not have to run a wire through the firewall.