1990 Ford Bronco full size

I have been getting a code 18 which is a loss of tach signal. I have checked the distributor and the module and they are both good. Where do I start next?

This vehicle should be equipped with a TFI ignition module setup and these were prone to various problems.
It’s the little gray module on the side of the distributor and testing them is often an exercise in futility. They may test fine a dozen times in a row and still be faulty.

There are other things that it could be but considering the module history it’s always a suspect.

thank you…we will try this. what others things are options in your opinion?