vw gasser tachs run off the ign coil. vw idi diesel tachs run off the alt W terminal. What is the frequency of the tach signal (relative to crank) of the ignition coil and the alt W terminal output?
someone had theirs on an oscilloscope, you'll have to search
I hooked up a MK1 gasser tach to the W terminal of my 92 Eco alt. Had to rev the engine before the tach would register and then it would read 3000 rpm at an idle of 1000 rpm. I won't pursue running the tach on the alternator (on my Caddy) any further and stay with a mag pickup and trigger.
vw gasser tachs run off the ign coil. vw idi diesel tachs run off the alt W terminal. What is the frequency of the tach signal (relative to crank) of the ignition coil and the alt W terminal output?
Based on my post above and what little else I know, I am going to answer my own question.
The ignition coil signal is 2 x crank speed. The W terminal signal is 6 x crank speed.
Thanks. I know about the tiny tach. I personally do not like digital tachs and prefer an analog one.
Gotcha on that - I wonder if there is an analog tach that works of the same "pulse" signal from the injector line?
Gotcha on that - I wonder if there is an analog tach that works of the same "pulse" signal from the injector line?
Probably. Technically it is not difficult to do, just more expensive since a meter movement is needed. Then you have to find a spot and custom mount it. For me, I prefer an OEM looking analog tach in the instrument cluster.