I marked the TIU. Make sure it is unplugged.

The resistor is wrapped in tape. It should be on a blue wire on the engine harness side of the C4 connector. Depending upon how the MSD ignition was wired into the car, that could be affecting your tach signal, too.

If you haven't done so already, visit the Resources section of this website and find the factory service manual for the 260Z. (Hint - Look at my signature for a shortcut.) It can help you a lot. For instance, the tachometer wiring schematic can be found on page BE-33.

 

Problem Solved, I feel like an idiot.  One of the tiny screws holding the face to the tach had come off and caused the face to skew enough to cause the pointer to bind. Can you see it?  Tach works flawlessly once again!

Moral of the story:   LOOK FOR OBVIOUS $^!#!!

Welcome to the club. We tend to look smarter after we get done wasting our time on dumb things.

And thank you for providing your solution. You might be helping someone else in the future.

Edited June 1, 20213 yr by SteveJ