No need. If it sweeps during startup, then you have a different problem than what I had.

Does the speedometer work? If it does then you may have an issue with your tachometer sensor.

 

Yes everything else and all lights work . It worked when I put it on like 6500 miles ago ,cluster was new .
the tach wire itself is just not getting enough power but don’t know why. He battery is putting out the correct volts but enough power is not maki g it to the tach . I put I separate jumper wire from battery to the connection pin where it plugs into back of cluster and when I rev engine the needle is jumpy but at least it respond to throttle . But only sweeps at key turn without the jumper

 

To me it doesn’t sound like a ground or power issue coming into the cluster. It sounds like a signal issue. I’d test the tach sensor and the connectors between the sensor, cluster and power. Look for loose or corroded connections along the way. If there’s a ground issue it would be associated with the sensor not the cluster.

FYI - It may be difficult to troubleshoot the tach sensor because it’s not a constant DC voltage it’s a pulse waveform.

 

Lord this is why I’m not a mechanic .
I did see when I turn the key on bike not running that the battery volts is 12.3
but when I start the bike volts drops to 7 or 8 I hooked a marine battery to bike battery and the same result volts drops to 8 volts . when started .
I replaced ecm with one from ebay because I can’t find a new one . So there is 200.00 wasted . May just drive it without tach and call it . May just replace speed sensor for ****s and giggles and if that don’t work well my my

 

that should work. You can put 12v to a bare cluster no bike and everything lights up. It’s gotta be a bad cluster.