New Holland 7740 SLE E39 error code (2024)

Hello All,
I have a New Holland 7740 SLE tractor it is 4 wheel drive and I believe its a 1997. While mowing hay the other day I made a turn down hill and the tractor went out of gear and freewheeled. It showed a E39 error code. I shut the tractor off started it up and it ran fine about 20 min later going down hill it kicked out of gear again. I was running it in 5th low. If I put the tractor in low 1st through 4th it will stay in gear but any other range and it free wheels and shows a E39 or E38 code. Any thoughts or help would be greatly appreciated!

E39 is C4 clutch solenoid open circuit and E38 is C4 clutch solenoid short circuit. Have a look at the solenoids on the side of the gearbox and check the connections. The big multi plug above the battery(assuming it to be the same as the older prequads) is a common place for corrosion. Sounds like a bad connection or faulty solenoid.

Thanks so much for the information! I am trying to locate the gearbox. Could you tell me where it is located on the tractor? THANKS AGAIN!

Found them. THANKS FOR THE HELP!!!

Ok so I checked the solenoid. Oddly enough it was fairly corroded. Actually the nut that holds it on fell apart. I cleaned it up and tried it once with the solenoid disconnected and it threw the E39 code. Plugged it back in started the tractor up and it moved foreword. Took it for a test run and I noticed when going through the gears the transmission low oil pressure light flashed every time I shifted when I started down a hill it again immediately free wheeled and flashed the E39 code. Any thoughts? Thanks again!

Try swapping that solenoid over with another.When it warms up,the coil may be letting go. Also,the accumulator---the black cylindrical thingy near the solenoids(I think), may need recharged.Low gas pressure in it will cause the light to flash.

Ok swapped the solenoids around and still have the problem. I referred to service manual about checking the accumulator. Took it off emptied all the oil out of it and tried to find the button they say I need to push on with a 10mm rod but I cant find it. There's just a hole and I place the rod through it and cant seem to find a button. I feel something nearly at the bottom you think that would be it? If it is I cant push it down so that would mean the accumulator is charged correct? Hey again thanks for all the help on this!

Does it mention a transmission calibration procedure in the service manual?
Click for calibration procedure
Best to connect a 12volt small 5watt bulb across the solenoid and wire it into the cab where you can see it, obviously it should be on at all times when the solenoid has power?

Ok so I really went over all the suggestions and discovered that the E39 code only occurs when the tractor is on a grade. If I back down a hill the transmission works fine but if I drive foreword down the same hill it hits the E39 or E38 code. I checked the oil and it shows full but I am thinking that maybe there is a leak on the suction side and when I get on a incline I lose oil. What if I over fill the system? Maybe add a gallon or two and see if that fixes the problem. Again it only occurs when I am facing down hill. I am going to calibrate the transmission tonight to see if that helps before adding the fluid. THANKS AGAIN!

Yes try that, but not too much or you will put pressure on the shaft seals. There would be a vent somewhere (see manual) on the top of the casing, might be worth checking to make sure its not blocked, before you add more oil.

Ok so I added 4 gallons of hydraulic fluid and at first it seemed as if it worked but if I get on a step incline it still free wheels. I noticed the hydraulic filter is slightly vibrating and there is a real high pitched wine, I guess you would call it that. Anyhow I think it must have a leak on the suction side of the hydraulics. Could a solenoid be not closing any thoughts? I want to say again thanks guys for all the help I am also putting all this up so in the event someone else has a similar issue this may help them. The one point I want to make is the area where I farm is very steep and when a issue occurs it out and out freewheels which is very serious I nearly rolled it the first time it occurred. I am very surprised there isn't some sort of safety that would prevent this. If I fix the problem the tractor is being sold because I cant chance a problem occurring and the future and the tractor rolling out of control. Thanks again guys!