[Fishmonger]

After my 18,000 mile service (perhaps coincidently) my tach needle began sporatically jumping around. It can last for seconds, or for as long as 5 minutues, then it returns to normal operation.

I thought it might be related to the charging system as it first occured when using my heated clothing, but now happens for no apparent reason. The bike has a new battery that I keep on a tender and there is no evidence of charging problems. I assume a possible loose wire, or the beginnings of my tach going out.

Anyone have any experience with this problem?

 

[oyrider]

My tach started jumping around, then read 1/2 of actual rpm, then quit altogether. This was at 7000 miles. The instrument cluster was replaced under warranty, and it has been good since.

 

[jcns]

check for loose wires to and from the speed sensor.

 

[whippersnapper]

My monster had similar symptoms and then the tach quit and permanently pointed to 7,000 rpm. This was a known fault apparently and the solution was to replace the entire instrument pod

 

[pcv57]

There is a plug on the back of the tach where a harness plugs in. I would make sure it's seated correctly first and that none of the wires are shorting out before replacing the tach.

 

[Fishmonger]

Played with the wires around the tach as best I could with just the right dash panel off. As it is working normally right now you cannot tell if jiggling the wires helps. Everything seems secure, so I just have wait to see if it does it again.

 

[carlspackler]

I've got the same issue on an 02 ST2 w/ about 10k miles, no real rhyme or reason but usually when I turn it off and back on it works again for a little while.

 

[Shazaam]

Electronic tachometers give erratic readings when the base voltage is low, usually caused by a loose battery connection. Check this first.

The worse situation for low voltage is at idle when the alternator output is at it’s lowest. That, combined with running high-wattage heated clothing, is the reason your tach misbehaves. You’re probably looking at needing a new battery soon.

 

[DesmosDromos]

I've seen similar symptoms on an '05 Monster 620 and an '06 Monster S2R 800. In both cases turning the bike off and restarting it fixed the problem and the dealer couldn't find anything wrong. Although it still infrequently reoccurred on both bikes IIRC.

 

[SS904]

Mine does it when I am at a light (at idle) and have a higher than normal load on the system. If I have the high beam on, brake light on and directional flashing, it will do it. If I turn any of the above off, it will stop. Pretty sure it's time for a new battery in my case. You could check for a loose ground too. I've read people finding the ground wire right there at the ECU causing the problem if it has a poor connection.

BTW the 04 and up bikes are completely different. You guys have the new instrument cluster. 03 and older have the older style. He could get away with just replacing the tach if needed. Not the whole cluster.