I think removing the belt would be easier, just loosen it and set it aside, no need to take it off completely.

 

Just pulled the flying lead off, tach went to zero, scanner showed 900 rpm (cold idle). Guess ECU must monitor something else, or "calculate" it from crank position sensor, etc.

 

I had that problem, it turned out to be the instrument pod ribbon leads needed to be re-seated. No problem with the tach or my alternator in over three years. YMMV. Good luck.

That is the kind of input I was looking for. A loose or cracked ribbon cable is my new prime suspect. Thanks.

 

Removed the little non-bolt wire, tachometer didn't work. Plug it back in, back to the way it was (still sticky) but I noticed that it stuck less than before (stuck for about 2 seconds after startup, then stuck for a few seconds while driving, then didn't stick at all after that.)
I didn't notice much corrosion on the wire coming from the alternator, nor was it loose.

 

Sticking at a reading above zero would almost always have to be mechanical, perhaps bouncing on the trail will slap it back to reality. The tach counts pulses from the alternator, which vary in frequency by speed of the belt.

 

It does sound like it is within the meter movement. Not the signal input to the meter movement.

 

Simpson 260s don't bounce well either.

 

Many many years ago, I worked at Brownell Electro for a few weeks. They are in the Atlanta metro area, just off S-75 approaching Atlanta. I had just gotten out of the Navy and had done flight controls and instrumentation as an Aviation Electrician.

Right after they hired me, one of the other techs was in a bad motorcycle wreck and was out for a while. They threw me right into building a variety of meter movements and custom instrument panel faces. What a trip that was, like working on fine watches.

I got fired after taking the bosses secretary to lunch one day and bringing her back wasted. I could not help myself, she was so beautiful. And it was her idea to go to lunch with me. The boss got so mad when she came back late and unable to sit up in her chair.

The Old Hickory House had Margaritas on special that day and she coulkd not hold her Tequila very well.