Adding a tach to 06 FXDI SC. The wiring instructions from the tach are:

Red wire to Ignition "On" DC 12V
Blue wire to Lamp On
Black wire to ground
Green wire to Negative terminal of coil

I wired the Red and Blue wire to the orange ignition wire off of the back of the speedo. Also hooked the black ground wire to the ground wire on the speedo. Turn the key on, the tach lights up and briefly jumps up and back down.
Ran a wire down to the ECM and tapped into the number #5 wire (Light Green & Violet) off of the ECM.

Doesn't work, when I start the bike it goes up to about 2,000 RPM doesn't change as I rev the engine.

Do I need to go directly to the coil to grab the negative side? Also, all of the ECM plugs are full, so I don' have an empty one to plug into.

Thought I would check with you guys before I tap into anymore wires. I am close, just a matter of getting the right connection.

 

What kind of tach is it? If the tach isn't designed to read the serial data info then the green/ violet wire isn't going to work and you'll need to tap into the coil

 

Thanks for the guidance. It is an aftermarket non Harley tach. I wired off of the coil and it is working now.