E4OD code p1728 - PowerStrokeNation : Ford Powerstroke Diesel Forum
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post #1 of 2 (permalink) Old 09-17-2018, 06:17 AM Thread Starter
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Ed Woods's Avatar
Join Date: Sep 2018
Posts: 2
E4OD code p1728

Need some trans help with my truck. 97 f250 hd with a 7.3 and e4od trans. It has been kickin my but for a month. So since I got it. It came with A rebuilt trans that had less than 9000 miles on it. Finally able to drive it after engine repairs and electrical work. So it shifts hard. All the time. After a bit it starts flashing od light code is p1728 torque converter slip. I have a scanner and can’t tell you when at 45 in od the tcc % is 0. Also downshifting is harsh. At 20 it’s still in 3rd. And you can feel it drop to 3rd. It lugs real bad until it stalls. Unless I feather the pedal and drive 2 foot. Put in neutral start it up again and put in drive and it’s in first. I have pictures of scanner reading as well. Fluid is perfect pink and not burnt. I can’t condem it for yet another rebuild or converter without bein 100% sure. I’ve already invested $5200 in a month. Any help would be very helpful. Thank you
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post #2 of 2 (permalink) Old 09-18-2018, 12:00 AM
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Mark Kovalsky's Avatar
Join Date: Aug 2007
Location: SE Florida
Posts: 3,019
Re: E4OD code p1728

Is that the only code? That code indicates that when it's in fourth gear and the converter is supposed to be locked, something is slipping. It could be a clutch or the torque converter clutch.

But your symptoms indicate that the converter clutch is locked when it shouldn't be locked, which will cause the stalling.

You can try driving it with the trans connector unplugged. That's the connector on the passenger's side of the trans. With it unplugged, it will only have fourth gear when the shift handle is in OD, and it will have second gear with the shift handle in 2. The torque converter should never lock in this condition. This will tell if the problem is inside or outside of the transmission.

Former Ford Automatic Transmission Engineer

“The good thing about science is that it's true whether or not you believe in it.” ― Neil deGrasse Tyson
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