shift light install help

[Dakin]

i have bought a proform shift light 67005sc ( http://www.proformparts.com/catalog/tachometers.html ) and i am told that it has to be connected to a positive, a ground (no problem) and the negative of the ignition coil or the negative of the electronic ignition to the tach. Obviously fto's don't have a standard ignition coil as it has more electroincs in it than a space shuttle, but does anyone know where the electronic ignition is or has anyone fitted a similar shift lightand has some tips?

i have tried connecting it to the back of the rev counter by taking out the dash pod, the shift light works, but as soon as it comes on the rev counter goes to 0 and stops there even when the light goes out. I have also tried connecting it to the rpm signal that feeds the ecu, but this has exactly the same result on the rev counter.

Please help, this is driving me mad!!!!!!!

Cheers Jason