At 12:47 AM 10/2/2009, Don Hanson wrote...
>Last week I was looking for a working odometer.  Found one on the
>Samba and
>got the whole cluster.  I also have a working tach from a diesel van
>   But, where is a good place to take a signal for the tach?

The signal for a _gas_ engine tach is taken from the coil. Diesels have
no coil, I don't know for sure on a Vanagon, but typically they get a
signal off a special terminal on the alternator.

I see two potential issues: first, the signal off the coil is
relatively high voltage (~100V spikes, if I recall correctly), which
the gas tach is designed to handle. Don't know what a diesel tach
signal looks like, or whether the high voltage from the coil might harm
a diesel tach. Second, a gas tach will receive 2 pulses per revolution.
I don't know if a diesel tach is calibrated the same, since the signal
depends on the pulley ratio between the engine and alternator.