So I did a gauge cluster replacement. Put an SR5 cluster in mt '82 and did all the wiring changes necessary to make everything work. Ran a wire for the tach. Weird thing is the tach only works occasionally.
Any ideas out there would be appreciated to try and trouble shoot the problem.
Thanks!

 

So I did some research on this site today and several people with the same problem stated when it was warm in the cab, their tach works, when it's cold, it doesn't. So I got home from work today and put a small space heater in there for about an hour. Nice and toasty inside, fired it up and tach worked great. That's weird. Now I have to figure out why?? I guess it wil work in the summer...

Anyone ever heard of this?

 

This could be a broken solder joint on the circuit board that completes the circuit when it is warm in the cab.

Check the back of the circuit board very carefully. Broken solder joints can be hard to see.

 

This might help:

 

I will check it out. Thanks

 

How do you put it back together after cutting the tabs and plastic retainers off?

 

I’m just studying the pics and it looks like that plastic piece cold interferes with the tach assembly? It looks like that little yellow piece doesn’t structurally hold much so I think you just re assemble less that little plastic piece you cut?? There might be a vid on you tube that shows taking one apart and putting it back together to give you a better idea??.

 

You got it - that piece it tells you to remove isn't important structurally, but it restricts the movement of the tach.

I think it will make sense when you take it apart and compare it to the pictures.

 

Well, I did it and removed that piece. And it didn't work. Oh well, I'll just live without a tach when it's cold outside...