drk1313

After reviewing the threads, I by-passed the filter and plugged the tach wire from the firewall directly into the distributer - no difference. The tach needle moves down slightly when I turn the key and remains pinned to ZERO. At this point it looks like the circuit board is the issue?

My connection on the distributer has two wires coming out of the 'tach' plug - one goes to the filter, the other is a blank plug. I was able to bypass the filter by using the second connector.

I just want to be sure I'm on the right track. I have the directions to pop the tach out of the dash - I guess I should order the replacement board to be ready for the next step.

Thanks!

7T1vette

My 'troubleshooting' process would be a bit different. The first course of action would be to assure that the wiring from distributor/filter/board/tachometer is sound. Next, a functional test of the tachometer with a 'simulated' signal should be attempted, to assure that the tach head is NOT the problem. Finally, I would disassemble to reach the tach circuit board and look it over well to see if there are any broken copper tracings or other damage. Or, if there is obvious heat/burning, try to locate the cause.

Then, if a cause seems apparent, attempt to repair it and try out (while still semi-disassembled). If that is successful...and the repair seems reliable...button it up. If "no joy", buy the board and the tach filter, and see if that works.

I think Willcox (CF vendor) has some info on-line for diagnosis and/or repair of the tach circuitry. You might see what you can find there.

drk1313

Fixed the tach with the Willcox replacement board - followed the video and everything went as outlined. Another dead '80 tach is back up and running. Great product and installation help!