Re: Tachometer gone mad

[Robert Ducker <bducker@domain.elided>]

Do both cars have the same kind of radio? If not & especially if the "mad"
one has no radio, you might try a filter capacitor accross the tach. A 100
microfarad at 25 volts from the tach battery supply terminal (if it has
one) to ground may work. If it does, he could choose to keep the capacitor,
or replace the tach, or just buy a new stereo!
Yes, this would be a pretty unusual problem & assumes that the more likely
suspects have been eliminated.