I have been having issues with my EOT temps ping-ponging from a lower then it should be reading to what I would think is normal. An example is I have seen it be at 195 and then suddenly drop to 175 for a few seconds and then jump back up to 195. It has done this on and off the past few months but never really done it for more then a few seconds to a minute maybe.

However a few days ago I was towing a tractor for my uncle-in-law and the EOT started doing the same thing but this time it stayed that way for an hour or so. Eventually I dropped the tractor off and the trailer and awhile later it returned to normal temp out of the blue.

The other day I caught it doing it again but this this only for a about 5-6 minutes.

Is this a sign EOT sensor going bad or something more sinister?

Obligatory pictures...

Picture from the day I towed the tractor. There is no possible way the EOT was that low. Later on out of no where it featured to a normal temp reading.



This was the Ford 8000 of his. Thing was heavier then it looked. My uncle-in-law had me take it to an Amish guy that does it engine work. He was discing with it this past spring and from the sounds of it something went in the head.



We haven't had rain in about a week but we got a boat load before that. It was still a bit greasy in the field where it had been sitting.



Same weird reading happened again the other day.



5-6 minutes later it was back to normal.

 

You could try swapping the EOT and ECT plugs around, and see if it follows the ECT readings.

 

Like Navi above said...... BUT FIRST, while it is reading a low temp when you know it should read higher, try wiggling the plug while monitoring it. If it jumps up then you know it's a bad connection. Just disconnecting it and plugging it back in may cure it.

 

I haven't tried unclipping the connector yet and connecting it again. I did check it was at least clipped on tight few weeks back. Next time it happens I will try wiggeling the connector.

 

Yep, had this same issue 2 years ago. Ended up being the pigtail. Replaced it and the problem went away.

I might add. You would want to follow the wire back a bit and make sure it's not chaffed. Mine was and oil residue on it. Soldering would be best but is hard to get to where mine was chaffed. Anyway, use heat shrink once you do the repair and make sure you not rubbing on anything. Cover with wire loom and tape.

 

Thanks. Sounds logical that it would be the pigtail. I'll have to investigate more next time it happens.