Weird Tachometer and Cruise control gremlins

[ripplesouth]

When I have the cruise control turned on, and I am in cruise at speed, the cruise control suddenly cuts off and at the same time the tachometer (engine rpm) drops to zero rpm (engine is still running), and the car drops out of cruise. It takes several minutes for cruise and/or the tachometer to come back on. I cannot reinitiate the cruise control for several minutes.

Where do I start with my diagnosis?

[Legacy777]

Does the tach go completely to zero? If you rev the engine, does the tach move?

[ripplesouth]

The tachometer does not respond to RPM signals. It flatlines to zero and does not move. It basically says that the engine is off, even though it is not.

I hope that makes it more clear

[86ruguy]

i can't confirm the cruise control problem(only because the car doesn't have it), but when my alternator was starting to go out, my tach was acting funny and the one of the local shops told me that it was the alt..

since replacing the alternator, no more tachometer gremlins

[ripplesouth]

That's odd, it's the second time someone has said something about alternator...Perhaps it's time for a 2 farad capacitor install...