4r100 shiftin problem
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Freshman User
Joined: Jan 2006
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From: Fort Ripley MN
4r100 shiftin problem
I have a 2001 F350 with a V-10. Tranmission will not shift into second gear without letting off the throttle. It did log fault code P0781 one time. Also when you put shift lever in second gear and take off it still takes off in first gear. Also down shifts into first gear hard sometimes. Hooked up my scanner and found #1 solenoid stays on after #2 solenoid comes on and will not go to off untill I let off accelerator. I do not have a diag. manual for trans and looking for help.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,730
Likes: 2,658
From: SE Florida
I suspect your trans might be one of the few gas engine trucks that slipped out of the plant with a mechanical diode one way clutch. What you have is the exact failure mode of the mechanical diode.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,730
Likes: 2,658
From: SE Florida
There are no markings on the trans that will tell you if there is a mechanical diode inside. I've heard, but never verified, that if you jack up both rear wheels and turn the driveshaft that you can hear the mechanical diode. It will sound like a ratchet. I've never had a mechanical diode trans to be able to try this.
Often as the diode fails it drops pieces of metal, not flakes or shavings.
Often as the diode fails it drops pieces of metal, not flakes or shavings.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,730
Likes: 2,658
From: SE Florida
No gas engine truck was supposed to have left the factory with a mechanical diode. Several thousand were built before the problem was discovered. I didn't work on that program, all I know is what was officially told to us in other engineering areas. We were told that all gas engine trucks that were built with the mechanical diode would have the transmission changed before leaving the plant. I can see how a few may have been missed. I have heard from a few people that have had transmission failures in 2001 gas engine trucks and found a mechanical diode inside. I have not personally found one.
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Thread Starter
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Freshman User
Joined: Jan 2006
Posts: 29
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From: Fort Ripley MN
I have transmission dissassembled mechanical Diode is failed. So time for rebuild and reseal, install one way clutch and new torque convertor. Thanks again for your help and great advise Mark.
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