dead tach

I went on a shakedown ride last week to see if all my electrical was up to par. Everything went great, rode around for an hour or so. Parked my bike, went to start it up a week later and my tach is dead. When I first turned the key to on, the needle jumped a bit and all the lights turned on but when I start the bike the tach needle doesn't respond at all.

Let the bike sit for a day, went back to turn it on and the needle does the same initial jump when I switch the key and then nothing at all. Can someone point me in the right direction?

 

Sometimes the Bike don't want to get rode that day.
Ain't but one way it can tell you.
The Tach goes on Strike.

When that happen to me, ... I tap on it a little bit.
If nothing happens ...
I tap a little bit harder.

If that don't work I start telling the Bike stories, of how ... when I get home ... I'm putting it for sale on Craigs List with a comment of how well it could be made into a chopper.

That's all I do!

 

I gave the tach a few love taps. When that didn't help I upped the intensity of the love taps but still nothing. The light on the tach works, and the needle will ever so slightly jump when I turn the key to on after it's had a chance to sit.

Robert mentioned taking apart a dead tach to resolder some connections, I really hope this isn't the case. Any other ideas before I have to crack this one open?

 

Are you seeing an input signal? With an analog meter set on voltage (0-10V) I'd watch and see if you see a pulsing (medium to high frequency) on the meter. Or if you are fortunate to own one (or know someone who does) use an oscilloscope and look for the signal.
Barring that, I would assume you have a weak or broken connection. I'd open that thing up and have a peek. It could be something really easy, like a loose screw.

 

I'm pretty new here but I thought I'd delurk for a moment and share. I fixed my tach almost by accident.

It stopped working. Actually it worked when I started the bike parked on the side stand, but when I sat down or moved the bars from left lock to center, it quit. It was maddening. I checked all the connections in the cluster and headlight bucket and I swear, swear, swear that I was getting a signal up to the tach on my multimeter. So I started looking for clusters on ebay. (As an aside, I later obtained a wiring diagram and yes, I was checking it incorrectly. ).

A few weeks later, I was cleaning my bike and noticed a crack in the harness sheath under the steering head, right where it flexes. I went to get some vinyl tape and figured I'd take a peek inside before I wrapped it up. One broken wire. I took the bike off the center stand, put it on the side stand, turned the bars full left and looked again. One broken wire, bare ends touching. :idea:

I soldered a same AWG splice in, wrapped it up, and all is well.

 

Robert - I hooked up a multimeter to it and without cranking the engine the tach is getting +0.6 volts across the wire going from the coils. When the engine is being cranked, the voltage spikes around. It's too fast for me to really notice, but I'd say roughly from 0.45 to 1.95 (although I saw a spike at 5 volts once).

I take it this means I need to take apart the housing and check for loose connections?