More Sticking Tach.

[Hal Taylor <taylor@xxxxxxxxxxxx>]

I posted recently about the strange behavior of the tach in my '86
spider.  It basically sticks wherever it happens to read when the engine
is put under load, and then springs back to life when load is taken off
the engine.

Brian Shorey suggests that it sounds like an electrical problem, most
likely with a ground (Brian, your response is very much appreciated -
thank you!).

Can anyone think of anything else that seems likely?  Why would it
freeze under engine load?  Where does the tach get it's input data, and
how is it transmitted to the gauge?  Embarssingly enough, I don't really
know how a tach works.

And if I'm to check grounds, where (specifically) should I be looking?
Is there a primary ground for the gauge that's a likely culprit?  I
don't relish the thought of pulling the dash apart to get behind the
instrument cluster;  is this as a big a deal as I'd guess it to be?  Is
there something on the sending end to check?

Thanks to all for any light you might be able to shed (and Brian, thanks
again for giving me a starting point).

Hal Taylor
'86 spider veloce "Strega"
driving by ear in Venice, CA

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