2001 JD790 Tachometer Jumping

   / 2001 JD790 Tachometer Jumping #1  

pretendfarmer

Gold Member
Joined
Jul 15, 2013
Messages
253
Location
WA
Tractor
John Deere 790
This just started happening the very last time I used it for the season. Any ideas on what could be causing this? The tractor only has 500 hours.
 
   / 2001 JD790 Tachometer Jumping #2  
On my skidsteer, it was an indication (in hindsight) that my alternator was going bad. Eventually the tach just stayed at zero. Happened twice - first time six years after i bought it (new), and a second time almost exactly six years later (just put a new one in last week).

A simple quick check is start the engine and see if your battery voltage is up (charging)
 
   / 2001 JD790 Tachometer Jumping #3  
This just started happening the very last time I used it for the season. Any ideas on what could be causing this? The tractor only has 500 hours.

I believe the JD 790 has a cable activated tachometer. Might be that you have to replace the cable..??
 
   / 2001 JD790 Tachometer Jumping #5  
If you have a mechanical cable try lubricating it - graphite works well. Make sure both ends are secure. If the knurled nuts start to back off the cable may no longer be fully seated.
 
   / 2001 JD790 Tachometer Jumping #6  
So does chassis grease actually. At 500 hours, cable replacement seems unnecessary.
 

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