Wacky Tach

[mrfixitct]

wondering if anyone else has seen this. Perhaps since I dont generally turn on the nav lights on our Sportster 155 I hadn't noticed this before. Turning on the nav light switch makes the tach go nutz, sometimes going back to zero, sometimes pinning the other way, though the engine is running fine..???

 

[TimIHB]

Mine did that when i ran the battery to low. I charged it up and problem fixed. I ran the radio on the beach too long.