Fluctuating Tachometer Fixed!

[jerseyguy123]

Guys, I wrote last week about my tach fluctuating and staying at 3000 rpms when it is usually at 2K when
I am at 70 MPH. Everything is back to normal, any idea what went on? Thanks and Merry Christmas

 

[danez_yoda]

if it fixed itself it will probably be back. research the RPM sensor that the tachometer uses and the wiring involved. likely a loose connection or faulty sensor.

 

[Kestas]

Mechanical devices never fix themselves. You have an intermittent problem.

 

[CharBaby]

I have thought about intermittent grounding.

 

[JMJNet]

What kind of car/truck are we talking about?
I have never had issue in my Toyota.
The GM is another story.

 

[Errtt]

I had a tach that would once in awhile go tach whacky on me. Every now & then the RPMs would go high.
Thought it was a connection, cleaning & Deoxit etc. didn't fix it.
So I took it apart, replaced a transistor on the PCB and it has been fine since.

It was a good thing I had a assortment kit of transistors. Kits of capacitors (electrolytic & ceramic), resistors, inductor's, diode's etc. sometimes come in handy.