A few weeks ago I noticed my tach needle "twitching" a bit, mostly right around 2800 rpm. It got worse over the next week until it was going completely spastic. After reading a bit, I figured I had a harness problem around the steering head, so I pulled apart the cowl and untaped the harness back into the plastic guide on the frame ('06 XB12Ss). I thought I might have found a bad splice, so I repaired it and put it all back together. It seemed good for a day or so, but the twitch came back.

Since the tach wiring is pretty simple with one wire straight from the VCM to the instrument cluster, I figured that either the wire had a problem deeper in the harness or it was an ECM or cluster problem. I have a lot of experience in the automotive industry with wiring harnesses and connectors, and while the ECM connectors are well sealed and robust, the connector at the cluster is not, regardless of the little rubber "bootie" installed over it.

I started with the easiest possible fix - Dow Corning #4 Electrical Insulating Compound. I lightly filled the harness connector sockets and reconnected it to the cluster. I've ridden several hundred miles since and I have yet to catch the tach doing it's little jig. Thankfully it was that easy - keeping my fingers crossed that it stays fixed!:D

Chris