Erratic tachometer reading on CK35 HST

[dustinfox]

Anyone know what would cause the tachometer on a 2010 CK35 HST to bounce around eratically? Sometimes it holds steady at lower RPMs but as the engine revs increase, the tachometer begins to flutter erratically. Aside from that, the tractor seems to function normally but the RPM needle goes crazy. Is there a sensor that can be replaced? Or could it be the gauge itself?
Thanks

 

[ptsg]

Check the wires at the back of the alternator and if that doesn't work, try to pull the plug in the back of the dash, inspect for any obvious dirt or damage, clean it and put it back in.

Usually, the RPM signal comes from a single wire on the alternator.

 

[Roadworthy]

The above may work if your tach is electronic. If it's the older type fed by a cable the cable may be binding a bit and need lubricated. You should be able to disconnect one end. You may then be able to pull the internal cable out of the sheath, lubricate it, and reassemble.

 

[dustinfox]

The above may work if your tach is electronic. If it's the older type fed by a cable the cable may be binding a bit and need lubricated. You should be able to disconnect one end. You may then be able to pull the internal cable out of the sheath, lubricate it, and reassemble.

Thanks Roadworthy... Here is what the 2008 CK25,27,30,35 repair manual says about tachometer operation:

"When the engine is started, the pickup sensor sends a
pulse signal to the pickup terminal of the display unit.
Then, the display unit processes and sends this signal
to the tachometer (4), and to the hour meter (15) on
the instrument panel through the hour terminal to operate
the tachometer and hour meter.
The hour meter operates based on real time regardless
of the engine rpm."

This sounds like I must have a pickup sensor somewhere but I'm not sure where it is or how to test it.

 

[rgr33]

I don’t know if this would apply to your tractor, but the same thing happened to my LS earlier this summer.
It turned out to be water inside the instrument, probably from hosing off the tractor after a dusty day of mowing

It went away as the summer heat did its thing

 

[mmecsics]

I don’t know if this would apply to your tractor, but the same thing happened to my LS earlier this summer.
It turned out to be water inside the instrument, probably from hosing off the tractor after a dusty day of mowing

It went away as the summer heat did its thing

Funny thing you said this, my friend has a CK2510 that is only a year or two old, every time after he washes it, the tach goes crazy. Then it goes back to normal, as I assume it dries out.

 

[dustinfox]

Ya, I don't think my issue has to do with moisture. It's been going on for a couple years now. I've been ignoring it because it doesn't affect tthe tractor performance but I'd like to get it fixed if I can. I'll start with the simplest things first and check the wires as ptsg suggested.

 

[ptsg]

After a couple days where the Kioti manual website wasn't accessible, I was finally able to download the workshop manual.

Looks like the pick up sensor they mention on the manuals is on the right side of the engine, towards the front. Also looks somewhat exposed to brush and sticks that could mess up the wiring, unless the hood covers it.

 

[Quickster2]

Mine is erratic in the winter for some reasons at lower RPMs. Never have figured it out. 2005 DK45. Not much of a concern as it works at higher speeds and all the time in the summer.

 

[dustinfox]

After a couple days where the Kioti manual website wasn't accessible, I was finally able to download the workshop manual.

Looks like the pick up sensor they mention on the manuals is on the right side of the engine, towards the front. Also looks somewhat exposed to brush and sticks that could mess up the wiring, unless the hood covers it.

View attachment 716713

This is great info! Thanks so much ptsg! I will check this out today.