My tach went bonkers. Please give advise

[TruckingToolMan]

Greetings fellow explorerman,
It happened one day out of the blue - I turn the key to start the engine and at power-up (accessory) the tach needle went to about 3,400 rpm. At ignition (starter crank) the needle bottomed out at past redline 6,000 rpm. At engine idling the needle returned to 3,400 rpm which was way far from normal since the idle rpm was true - at about 800 - 900. I proceed to drive and as I accelerate the needle went to about 4,000 rpm and stopped moving past that, but my real rpm were more like in the 1,500 – 1,700 range. when I slowed down to idle and stopped at a stop sign the needle returned to 3,400 rpm. Therefore, I conclude that my tach is certifiably insane. Any ideas or suggestions as to how I can cure it? Maybe it is shorting out somewhere? Please, consider that I am OK when it comes to mechanical problems but I am electrically “challenged”.
Thank you!

 

[ExplorerDMB]

That is very odd. I would try to take your cluster apart and try to look for anything noticeable. Good luck.

-Drew

 

[tonyd12345]

Very odd... Sounds like there is something going on electrical, probably a short somewhere. Welcome to the site.

 

[Brian_B]

I agree that it might be a short. My ranger's tach went nuts once. Come to find out, the wire was loose where it hooked to the coil. Check the wiring first before you take the cluster apart.

 

[jar2187]

On my 92 my tach is doing the same exact thing, it started about 2 days ago.