Crazy Tach.

[Confederate Forge]

So my dad has a 91 ranger with 4.0 and we cant figure out whats wrong with his tach. When the key is off it stays at 0 like it should but when you turn on the key it goes up between 3000 and 3500 rpm. Then it doesnt move at all from that spot until you turn the key back off and it drops back to 0. Sometimes it works right (once in a blue moon) but 99.9% of the time this is what it does. The other day while it was raining he drove it down the interstate at about 80 for not quite an hour and it started to work again. Then on the way back home it went right back to the same ole same. We think it could be a bad ground or something. It has been this way since he got it about 2 years ago. Any ideas??

 

[Confederate Forge]

I guess I got yall stumped on this one too.

 

[Ozwynn]

I would just replace it or just not care.

 

[Rouphis]

Sorry to necromance, but this seems to be a very common problem, yet no one have ever posted a solution. I trying pulling the gauge and tightening the nuts on the back to no avail. Does anyone have any useful insight to this issue?

-Rouphis