Rpm gauge bouncing

[Scoot5869]

2010 t800 cm871 rpm gauge was bouncing up and down engine light would come on and leave. This was at idle truck didn’t seem be running rough but was surging I guess with the rpm’s would bounce to 300-800 range. Don’t have my computer with me to check it. I was just curious as to what may cause it ecm has 1837 hours on it with the proper files. Replaced all the fuel parts but the gear pump this spring. So far a random occurrence. Will hook up insite tonight to see what’s on it. Any ideas let me know thanks

[Scoot5869]

The speedo will Also drop and the abs light comes on and off as well.
My t880 did this this summer with a paccar in it and it ended up being ecm. I would be surprised if a recon ecm only lasts two years but that’s sad if so.

[SquareOne]

Around here, the advice is to smack a suspected ecm in order to see if you can re-create the issues you're having.

Recons/remans seem to be hit and miss at best with many other parts. Quantity over quality is the typical with much of that stuff.

[Scoot5869]

Yea I know the trick that’s how I diagnosed the last one. However I’m in the middle of harvest and don’t want to brick it yet. I did t get chance to hook up computer yet either.

[Scoot5869]

So here are the faults that were on insite in the attached picture. I cleared them all and will see if the same ones appear again if it does its little dance again. I’m goin to check my battery connections and fuses pull the ecm connectors and check them when I’m not in windy dust conditions