Diode transmission?
Senior User
Joined: Nov 2009
Posts: 230
Likes: 0
From: Tampa, FL
The only thing I have ever read about this is something about a diode in the alternator that somehow effects the trans if it goes bad. This may be something completely different than what you're looking for but just thought I'd put in my 2 cents. lol
Fleet Mechanic
Joined: Aug 2010
Posts: 1,456
Likes: 155
From: Sedalia, CO
Many of the 2001 4R100's had a mechanical diode (switch - EDIT: See Mark K's correct evisceration of this term below. Clutch is the correct term.) ) that was prone to fail. Ford stopped using them in the middle of the model year, so later '01's didn't have them. My '01 X (Build in 12/00) did, and it's original tranny failed at 17K. The most common initial symptom is an unwillingness to shift from first to second gear.
Mark
Mark
Logistics Pro
Joined: Aug 2009
Posts: 3,609
Likes: 324
From: Arizona
Some 2001 trucks and excursions had transmissions that used a mechanical diode. It was/is prone to sudden failure. I just saw the build dates on another forum a day or so ago.
By now most of the 99-03's have had their trannys rebuilt anyways, mechanical diode or not.
By now most of the 99-03's have had their trannys rebuilt anyways, mechanical diode or not.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,704
Likes: 2,625
From: SE Florida
It's not a switch, and it's not anything electrical. Mechanical Diode is a brand name for a type of one way clutch. Here is everything you would ever want to know about it: Epilogics Mechanical Diode Website Homepage
They were in the 2001 diesel transmissions from the start of 2001 production in July, 2000, until March, 2001.
They were in the 2001 diesel transmissions from the start of 2001 production in July, 2000, until March, 2001.
Thread Ender
Joined: Dec 2010
Posts: 1,296
Likes: 8
From: SC
Old thread I know, but sometimes thats what you get when you search...
I doubt thats true.
Im looking at a truck with a 03/01 build date. Any way to tell whether it has the diode or not?
Im looking at a truck with a 03/01 build date. Any way to tell whether it has the diode or not?
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Fleet Mechanic
Joined: Nov 2008
Posts: 1,573
Likes: 4
From: Seattle
Mechanical Diode Tranny Build Dates2001 vehicles equipped with 4R100 transmission, having a transmission build date between
7/27/2000 and 3/23/2001.
Roland (mueckster) 04-15-2008
The trans does have its own build date located on the tag on the trans case (left side ,rear).
4th line down should show BD- #Letter##. This is the build date year/ month/ day.
Example : BD-1D28 1=2001 D=April (A=Jan, B=Feb...12=Dec) 28=Day of Month.
Using his example tranny Build Date is Jan 28, 2001
Mark Kovalsky 01-03-2009
The mechanical diode was in the diesels from the start of 2001 model year (July, 2000) and left production in March, 2001.
Cody (cleatus12r) 01-03-2009
If anyone is still interested, the "mechanical diode" was the replacement for the one way roller clutch previously (Intermediate one way clutch) used in the E4OD and 4R100s. After Ford found out that the diode wouldn't work in the gasser trucks (they exploded when shifted at 5300 RPM), they decided that they should stick with the proven and slightly more robust design. It is a mechanical device that allows rotation in one direction but not the other. It is used for the 1-2 shift when in drive range. When the "diode" was used, it replaced the roller clutch with a sprag that is inherently weaker. High power/high RPM 1-2 shifts are what kills the intermediate one way in the diesels.
Mark Kovalsky 01-03-2009
The gas engine trucks blew up the diode at 4600 RPM if the driver lifted his right foot just as the WOT 1-2 shift started, then put it right back on the floor. The person that discovered this was able to do it on 100% of the trucks he tried it on. That's why they left it in the diesels, they couldn't run 4600 RPM.
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