Tachometer trouble shooting 1990 flhtcu

[Traveler733]

Anyone have any tips for diagnosing tachometer on 1990 FLHTCU Bike runs good.  LOTS of miles..  New S&S HI-4 ignition last year. Tach quit not long after the new ignition. Wiring all looks good  Maybe a bench test procedure? 

[Thermodyne]

Its just a signal driven head.  Ground, lamp power, and signal are the wires.  I would just verify the ground and power, then use a old school dwell tach to see if there is signal from the coil.

Past that, where do you find a replacement.   The tach on my 84 went bad, the needle hangs up at 1000.  I'm on my second replacement from J&P and they both are bouncing all over the place.   

[Traveler733]

Thanks for the reply! I verified power and ground, at the rear of the tach. So, with your suggestion, I will test for signal from ignition. Good idea!   May have to remove fuel tank, for access to coil.. for further testing..

[Traveler733]

Found it!  It was a loose crimp, on a spade wire end connector..  New spade terminal, good crimp. Works fine! Thank YOU!