Lost Tach

   / Lost Tach #1  

fishmen222

Member
Joined
Apr 22, 2012
Messages
29
Location
Carson, VA
Tractor
John Deere 755
Was hogging through a bunch of saplings on a 1992 755 without side shields. Tractor runs fine, but lost tach. As tangled up in them as I was, I can not help but feel that I have pulled a wire. Any suggestions as to where to start? Thanks a bunch folks.
 
   / Lost Tach #2  
Hopefully you have the service tech manual for your 755. .. or not?

Look for a blown fuse.. looks like follow the yel/wht wire.

Attached is a portion of the schematic that shows which fuse in the fuse block.
 

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   / Lost Tach
  • Thread Starter
#3  
Thank you. I only have the owners manual, but that will give me a start.
 
   / Lost Tach
  • Thread Starter
#4  
Took the battery out and panel apart to get a better view. The yellow/white wire goes into a junction with a black and red coming out. The yellow/white appears to be a common gauge light wire as it also goes to the other bulbs. When I ripped out a sapling that hung up underneath, I did not use care as I thought everything down there was metal. There is a sheathed cable going to a sensor at the front of the crank down there. I fear I broke the internal cable (looks like a speedo cable). Seems simple enough to get to, but will run off of sound for now. When I get it out, I will determine if it is intact internally and see if I damaged the sensor or tach. Thanks for all the help.
 
   / Lost Tach #5  
The tach is totally mechanical using that speedometer like cable. The wiring is only for the lights. The cable inside the sheathing may be broken. The original factory installation of the cable included a rather sharp bend where it exited the engine. The replacement cable includes instructions for a minor relocation to widen that bend and improve the life of the cable. If the hour meter is still turning then the cable is OK and the problem is the tach needle. I have had both fail, and went for a few years going by sound. When the hour meter in the tach finally failed I replaced the tach and realized how much I missed having a functioning tach needle.
 

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