about to conect the rev counter and not sure where the best place to use is

either the negative terminal of the coil if so there are 2 green wire which one or the alternator if this one what pin do i use ????

Tri

definitly not the alternator.

tap in to one of the green wires from the negative side of the coil.

The light green from the coil goes to the rev counter on the Sierra loom.

If you should connect it to the + side of the coil the state of the lead never wil change....

if you connect it to the negative side of the coil... then when the engine is not sparking..the lead will measure 12volts..(battery volts)

if the engine sparks..then this is done by connecting the neg side of the coil to ground a realy realy short time....

the voltage then drops on the rev counter lead...

and that is what we want..

now the only thing we need to do is count the duration of when the leed is 12volts..if it its very long then the engine = of or on a ultra low RPM...etc..

on the same principels all sensors work of an car like ABS and Crank/Cam sensors..

TKS