lets do this another way,
sure scope the signal, sure, to see Polarity and PW, pulse width, (and the horror of back EFI is seen , the G16 has suppressor to stop that a module up front)
then use function generator set square wave pulse mode, a bench tool that can very easy generate pulse at slow rates (just like the engine does.)
then make the same pulse as the car but only 12vdc swing, 0,12,0,12, if that is the current baseline swing do that only
see the tacho does work and no COIL is needed nor wanted.
that is the best way to do that, or just remove the coil and use 100ohm resistor in place of your relay coil.
and get nice clean 12vdc pulses or 5v pulses if that is called for..
in the MS you can invert outputs of wrong, do not do that that to COP or it burns up fast.
if you dig into the G16 brown wire tacho line fully , reverse engineer it you see that they do all the can to get ride of the huge back EMF kick back pulse.
ours is near 400v, a very dangerous level in to any kind of silicon for sure MOSFET transistors.
some relays coils have built in diode clamp snubbers inside, so making this path totally unpredictable , both kinds, used on no maker of relay and p/n told.
not all relays are the same,.
sure scope the signal, sure, to see Polarity and PW, pulse width, (and the horror of back EFI is seen , the G16 has suppressor to stop that a module up front)
then use function generator set square wave pulse mode, a bench tool that can very easy generate pulse at slow rates (just like the engine does.)
then make the same pulse as the car but only 12vdc swing, 0,12,0,12, if that is the current baseline swing do that only
see the tacho does work and no COIL is needed nor wanted.
that is the best way to do that, or just remove the coil and use 100ohm resistor in place of your relay coil.
and get nice clean 12vdc pulses or 5v pulses if that is called for..
in the MS you can invert outputs of wrong, do not do that that to COP or it burns up fast.
if you dig into the G16 brown wire tacho line fully , reverse engineer it you see that they do all the can to get ride of the huge back EMF kick back pulse.
ours is near 400v, a very dangerous level in to any kind of silicon for sure MOSFET transistors.
some relays coils have built in diode clamp snubbers inside, so making this path totally unpredictable , both kinds, used on no maker of relay and p/n told.
not all relays are the same,.
http://www.fixkick.com