Grab an extra 12V battery (it can be pretty much anything including a cordless
drill battery in the range 12V-15.6V) and use that to power the tach. Make
sure that the tach ground is connected to both the negative terminal of the
'extra' battery as well as the chassis of the car. If your problem goes away
then it is the alternator, if it stays then it has to do with the signal
you're getting from the coil.
If the alternator has bad (worn) brushes then it can generate noise. A bent
shaft or shorted commutator on a generator can do bad things to tachs as
well.
If the problem is from the coil and the accel module, then try putting a
1N4003 diode in the line from the coil negative to the tach input. Try either
direction.
Hope this helps,
Theo
________________________________________
From: tigers-bounces@autox.team.net [tigers-bounces@autox.team.net] On Behalf
Of wsamouce [wsamouce@kc.rr.com]
Now a question for you all -
I am having a problem with the needle jumping around when the engine is at
idle. Once the rpm is over 2000, it reads correct. When I turn on the
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