Spastic tach

[mmcn49]

My Spastic Tack – Latest Observations: My tack like others in this thread randomly fluctuates. Earlier this season I noticed that it only fluctuates when I have the heated riding gear turned on, (grip heaters, gloves, jacket liner and boot insoles). Confirmed this by observations over a half dozen rides and hundreds of miles ridden with the heated gear both on and off.

The aftermarket voltmeter reads a steady 13.8 VDC with no heated gear and a steady 13.4 VDC with all the gear plugged in and turned on.

I own two, 07 XB12STT's. They're both set up the same. The tachometer on the second TT does not fluctuate with the heated gear plugged in and turned on.

Can't figure this one out. Open to suggestions.

[mriulvr]

I checked everything under the sun with no fix. Ultimately it was the ECM going bad. Bought a used one, updated the ECM settings, which I had to do using ECMspy because it was from a an 07 and mine is an 04. They are interchangeable but couldn't flash. Everything had been rainbows and unicorns since. Interestingly, my AFV has been much steadier aand runs much smoother. The bad ECM appears to have been causing issues that I was not even aware were happening.