New on here and have a 09 model MB HD I bought a month ago and noticed yesterday the tach / hr meter wasn't working like it was when I bought it got home and started checking the wires wtf? no hot wire? one red wire wrapped around the spark plug wire and a ground wire. Does this have a internal battery that can be replaced or time to buy another one?

I believe it's a tiny tach on those. The battery is internal and not replaceable.

1744 Phowler Prowler, 23 Dixie

Tiny Tach estimates the battery will last 5 years so yours was at it end it appears. Give BoatDr a call (504-737-1203) and get a new one. Just etch the original hours on the case of the new tach so you have a total.

Latest tachs have more features - service hour intervals etc... Will probably also have a white ground wire like the older ones- just ground it to the clamp on the wire harness and wrap the red wire around the plug wire.

thanks for the info