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7740 SLE transmission woes

Discussion in 'Repair & Technical Discussion' started by Cantrellc123, May 15, 2018 at 7:55 PM.

  1. Cantrellc123

    Cantrellc123 New Member

    7
    Jun 14, 2015
    My 7740 has developed a problem with the transmission. In colder temps-Nov thru May only the even numbered gears work. Once I shift to any odd numbered gear and release the clutch the tractor fails to move and code E39 mostly shows up with E38 displayed occasionally. I must shut down the tractor and restart to clear the code.
    Sometimes I’ll shift to an odd gear and it’ll be a few seconds before a code appears, other times it might be working perfectly in all gears. When the odd gears don’t work the clutch is harsh when engaged. Last summer once hot temps were the norm it was flawless but as soon as cooler weather arrived the problem resurfaced. I carried the tractor to my closest dealership and they concluded there was an electrical short in the wire harness. They opted out on trying to repair the wiring issue. My research on the internet indicates the problem lies with the C4 clutch solenoid if it is indeed a wiring issue. I can’t see any damaged wiring that’s connected to the C4 solenoid. I’m not an expert on wiring issues with a 7740 but I find it odd that the issue is effected by ambient temps. Regardless of how warm the tractor gets from use in colder weather the odd gears refuse to work but yet when ambient temps have reached beyond 90 degrees the problem disappears. Two days ago I used it to move round bales off of a hay field with no issues for an hour but then the problem resurfaced. Today I moved the tractor about 5 miles and no problem.

    Has anyone encountered anything resembling this problem?
     
  2. RC Wells

    RC Wells Well-Known Member

    Dec 25, 2008
    If memory serves me correctly, Ford used pulse width modulation to regulate the hydraulic pressure to the transmission. The PWM valve solenoid would fault and create the clutch jitters and erratic shifting. Temperature related symptoms too. Sometimes required replacement and re-calibration procedure. Other times re-calibration would solve the problem. Low voltage creates calibration issues.

    There were issues with a defective aluminum valve body on some tractors. The body was machined incorrectly and changed shape enough with temperature shifts to bind a solenoid spool.

    The main wiring harness to the transmission was another area of intermittent shift issues. The main plug above the battery case would usually be the source of the problem. In this case the harness was not actually faulty, but the connectors would corrode from moisture and require cleaning and packing with dielectric grease to keep moisture and corrosion at bay. Again a change in temperature would trigger the problem.

    Low voltage can also create the symptoms you describe. Usually the batteries or the alternator getting tired.

    The New Holland TS115 has the same transmission. Because all the Ford trained mechanics are now retired, describe the problem to the technician that works on the TS11 and its successors. Bet they have an answer for you.