Traction 790 John Deere Fuel and Temp Gauge problems

[timbertbone]

On my 790 John Deere the fuel gauge is not working and the temp gauge only works in the fuel tank is full. Any ideas what would cause it not to work or where to began to troubleshoot. Would the 790 Tech manual help troubleshoot this? Dose anyone have a PDF of the Tech Manual?

 

[Tbonetimber]

There are 3 different electrical systems on the 790, so you need to give a serial number. The 790 manual should help in troubleshooting. I think the side panels by the dash come off easily. There should be some electrical connectors visible then. Take them apart and clean them if needed. Then reseat them a few times. You are probably loosing the common ground connection. If you see any other connectors near the fuel tank or temp sender, do the same with them.

S/N- LV0790G294582
I have checked for loose connections. The weird thing is the temp gauge works great with a full tank of fuel. I agree with that I知 fighting a ground problem.

 

[beenthere]

Two names, same member??

 

[Wagtail]

Two names, same member??

Yep... it's the same username, just back-to-front. I suspect that he took K7LN's advice, logged off, went out to the tractor, got the S/N, checked for loose connections and then came back...
...and forgot his brand new password.
So he re-joined.
(I've been watching a lot of Inspector Morse mysteries as of late )
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G'day Mate and welcome to TBN from Downunder.

You've got a 1999 year 790, eh?

Enjoy the site.

 

[timbertbone]

That a little out there. How it logged me under a different use name. But besides all that. I still trying to troubleshoot my tractor. Does any one have a troubleshooting manual? or any ideas could it be a bad fuel gauge sensor?

 

[Wagtail]

According to your reported symptoms; the fuel level gauge doesn't indicate the level of fuel in the tank at all and the temperature gauge doesn't indicate the engine temperature at all unless the fuel tank is full. (when the fuel in the tank reaches a certain point does the temperature gauge cease working?)

Troubleshooting indicates that there must be an electrical 'common point' between the two gauges and that common point could be the fuel gauge sensor.

Do you have an Owner Manual? The fuse/relay diagram may show which fuse/relay relates to which circuit. If the relays are the same, you could try swapping then around to see if the symptom(s) transfer to another 'system'. I don't believe that it is a fuse because the temperature gauge will work under the circumstances you've provided.

You local JD Dealership should be able to provide you (for free, at least they would for me ) a 'print' of the electrical schematic for your tractor.

 

[skycranekid]

I have the same dash on my tractor and it's a very common issue. I've checked or replaced every single electrical connection on the tractor and finally figured out what the problem was. Your going to find this amusing but the reason our gauges don't read all the time has nothing to do with the electrical or wiring or sensors. THE ISSUE IS SIMPLE. The dash isn't sealed and moisture finds it's way into the dash and corrodes the needle mechanism itself. After all the work I did, I said F(*& it and hit the dash lightly and BOTH gauges started working instantly. So you have two options. Take your dash apart and lube the needle indicators or replace the dash or just tap it once in awhile if they stick. I've read countless threads of people saying to check "grounds" and power wires and sensors but the answer is quite simple and I wish someone had mentioned that before I went checking everything. If tapping your dash doesn't work your corrosion might be too severed to un stick in which case you will need to replace the dash. cheers!

 

[Industrial Toys]

Had a 770. Same (GREAT) tractor. Just ciurious on condition and hours.

YES, the business with the full tank of fuel effecting temperature almost certainly is a ground issue.

 

[skycranekid]

My 770 is in great condition and is a workhorse for it's size. I just moved 150 yards of gravel and fill with it last week no problem to build a pole barn pad. Mine has around 600 hrs on it and runs like new and is serviced regularly. I've owned a few tractors mostly larger and quite enjoy the size and maneuverability of the smaller 770. I think a mini excavator would fit nicely on the farm as the next toy.

 

[Industrial Toys]

Too bad, that same configuration with the large rear wheels was not offered in a hydro. A tractor with small rear wheels is really just a lawn tractor in my opinion. Maybe a sophisticated or glorified lawn tractor, but still that.