4r100 have to let off to shift
 

Ok guys i have a 2001 f-250 with 125000 miles on it. The issue is that it shift at 3500 rpms or when i let off the throttle i have changed the tps as well as oss or vss..... as well as the torqe converter.... now im at a loss for words does anyone have any help to give!?!? it shifts fine when i walk it on the colomb!!! do u think maybe a cks crank position sensor!!!!!
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You would have saved a bunch of money and time if you asked for help before all those "fixes."

You need a trans rebuild. The mechanical diode has failed. It needs to be replaced.

can i pull the transmission and replace this diode alone or is this deep in the tranny? may i ask what this does.....

i did the trq converter myself and the converter was slipping to be honest...... plus it was shudderring

hey thanks where would the best place to buy this part

Heed Mark's words...he helped designed this thing and knows it better than any of us do.

Btw, welcome to the club, I joined February 2006...exact same symptoms. I was crossing a railroad track and stopped at a stop sign. As soon as I started to accelerate, it did the same thing yours did and wouldn't shift until I let off the accelerator. A trip to a dealer confirmed the mechanical diode had failed and my trans needed to be rebuilt or replaced.

Get yourself a BTS trans and you'll never have to worry about this or any other trans issue again.

Tnx guys and thanks mark

John Wood in Holtville, CA does a nice job if you're located in the west.

John Wood Automotive - Home

Does anyone know the ford
part number of the mechanical diode

You don't need the part number of the mechanical diode. You can't buy one, they were discontinued because they were crap. You need to replace it with a sprag type one way clutch. Anywhere that sells transmission parts will have the right parts to do this.

Mark,

What years were the Mechanical Diode used? Phased out?

Manufacture Date June/July of 2000 to March 2001 any diesel truck with that build date may be affected. Mine was built in October of 2000 and it was affected...

That's right. It was from the first 2001 built and ran through 3/4 of the 2001 model year.

It was ONLY in the 2001 diesel trucks. Rumors continue that some gas engine trucks got out with a mechanical diode. It's certainly possible. Many, many trucks were built with mechanical diode transmissions before it was discovered that they failed at 4600 RPM. The mechanical diode was left in the diesel trucks because they couldn't reach 4600 RPM. All of the gas engine trucks were supposed to have the transmission replaced with a non-mechanical diode trans before leaving the plant. I could see how a few might slip out.

Not to keep poking. but mine sometimes wont shift into overdrive unless i let off the throttle. its a 7.3 The build date on the trans is 1e15. meaning it was built in may is it possible to have a mechanical diode. or is it a possible a sensor is going bad? i pull a close to a 10K travel trailer and wouldn't want to get stuck on the side of the road in the summer with family. I mean the kids i can deal with but the wife is a different story. :-blah lol

The mechanical diode only affects the 1-2 shift. It has nothing to do with the shift into overdrive. It is not possible for a trans built in May to have a mechanical diode.

At what speed won't it shift to ovedrive? Towing? On a grade? It may be the software preventing the shift.