Purchased a bike a few weeks ago&nbsp\\;\\\\\\;and the tach works sometimes and at other times doesn't.&nbsp\\;\\\\\\; Looked ath the connectors under it and they seemed tight.&nbsp\\;\\\\\\; What could be the problem?&nbsp\\;\\\\\\; Maybe a bad sendining unit or the tach itself?

 

what conectors did you look at in the tach or on the bike... i have my tach plugged in on the computer, but you may have&nbsp\\;a bad ground as well, some people try to do tach installs with wire crimps and not solder... bad move

 

The connectors looked like factory under the Tach assembly.&nbsp\\; Looked like all wires were tight within the connectors though.

 

did you check where it plugs into the bike, that is what you need to check, it is prob the main signal coming in that is creating your issue, not the plugs on the back of the tach

 

You don't say what year or model the bike is but HD changed the way the signal is sent to the tach and speedo with the 2004 model year.&nbsp\\; Prior to that, the tach signal was picked up off the coil, usually via a pink wire somewhere in the wiring harness.&nbsp\\; In 2004 they moved to a serial data bus that sends the signal to both instruments.&nbsp\\; You may have a bad ground as was suggested, you may also have a mismatched tach for the year/model of your Harley.

A little more info on the tach, year and model of the bike would definitely help out here.

 

I had his exact problem
&nbsp\\;
I thought and check all the things you stated
&nbsp\\;
I found that the tach wire was boken inside the insolation right where the wire started into the frame.&nbsp\\; It took me forever to track it down.&nbsp\\; If my memory is correct the wire is pink (maybe orange but I think pink)&nbsp\\; I simply found it, soldered it back and it has work with no problem since.&nbsp\\; My bike had a tank lift at the time.&nbsp\\; Not sure why it broke but that was the prob.

 

Found it.....bad ground.&nbsp\\; Works like a champ now.