So first of all, great forum and a lot of help just reading from sidelines. Thanks in advance guys (or maybe girls too.)
2nd I’m a long winded SOB and I just type as my brain spits out ideas so I’m also sorry in advance.

Here’s the deal. I have a 2000 F150 Harley. Original 5.4 (no rebuild) and Original 4R100 (also no rebuild) with 298,000 Miles on the clock. She’s getting up there but she’s still strong. Or at least she was ...
The other day pulling out onto the street about 1/2 throttle, the transmission shifted from 1st to 2nd perfect then shifted into 3rd. When it shifted into 3rd, it did a weird double bump (back to 2nd then right back into 3rd) and made a clunk and then rev’d like it was in neutral and never shifted up or down out of 3rd until after it coasted down in speed, then 2nd engaged again and it accelerated until the PCM commanded 3rd and it shifted into 3rd but ran away again never shifting into OD or back to 2nd until the vehicle speed slowed again. I pulled over and checked all the gears individually (1st 2nd Rev) and manually they all work perfectly and drive smoothly with no slip or hard shift until it is in drive and 3rd is commanded. The OD/Tow button lights up and goes out when cycling tow mode and, with OD Off (i.e. in tow mode), the shifts are again normal for 1st 2nd but only difference is it never tries for 3rd with OD off. I could have sworn (in fact I’m positive) that, when I towed before all this happened that it shifted to 3rd just not OD when I had tow switch on. Why it shifts to 3rd in D (and runs away) but doesn’t even try with tow mode engaged has me scratching my head.
Anyways, I started doing a little reading and from what I can tell about solenoid combinations, torque converter solenoid, Coast Solenoid, and the mechanical clutch and sprag combinations, everything seems to be functioning correctly electronically (in manual 1st and 2nd gear SSA and SSB combinations must be working both on and off because, duh, I have 1st and 2nd. In Drive, I also have 1st and 2nd but when SSA is commanded to turn OFF for 3rd in D, it shifts but no drive engagement for 3rd gear.
I was also reading about sprags and clutch pack combinations for the different gears and based on those combos, there is no one item that is not used in another gear or reverse so those seem to be all functioning as well. I have full powered drive 1 and 2 and reverse with no shudder or banging or soft shift. I also have engine braking when I let off so coast clutch seems ok. Also, to add confusion, I have no blinking OD LIGHT or any codes when I hook up my scanner and read the codes. (Except an ABS code I’ve been ducking)
So I’m down to 2 things. In order of probability:
1. The valve for 2-3 is stuck. Why it doesn’t just skip to OD when I let off throttle a little I don’t understand but I’m not totally clear on the relationship between third and OD. I thought it was just a change from a sprag clutch to a clutch pack When the TCC engaged but that’s a little fuzzy.
2. The 3rd gear (intermediate clutch) is toast. But, I read it was also used for 2nd which has no issues or slippage.

I guess there’s a three.
3. There really is an issue with SSA when it’s supposed to turn off in D and PCM commands 3rd. But, in my brain, I can’t see that, if it actually does shift into 3rd electrically just not mechanically( valve movement) If that makes sense to anybody.

Don’t know who the latest Guru is or if Mark is still around but, I could use some help to get my girl back on the road.

again thank you all for the information and opinions you provide. Stuff is really helpful.

 

Have you pulled DTCs or monitored the solenoid functions via OBDII?

Per the chart below, assuming your driving in D (referred to as (circled) in the chart), SSA shuts off and SSB is actuated when the PCM commands 3rd.

I'm including this in the event I am misunderstanding just what you're describing but, honestly, after researching, study, and reading back 8 years of 4R100 posts by members and subsequent replies by Mr. Kovalsky to solve my own shift issue, I don't see your issue being in the solenoid body as much as I think it may be a sticking valve.

I'm not a mechanic or a transmission expert like Mark, but without details of actual logged solenoid activity or DTCs, I won't rule out either solenoids or a valve in the main valve body.

That being said, Mark is still active here and, as always, very helpful with transmission problems. Give him time and I'm sure he'll be around.




Below are the tables showing what happens when the PCM commands the gears but the SSs are Always OFF. Following that are the tables for Always ON

Shift Solenoid Failure Mode Chart Always OFF

Failed OFF due to PCM /vehicle wiring concerns; solenoid electrically or hydraulically stuck off.

Shift Solenoid Failure Mode Chart Always ON

Failed ON due to PCM /vehicle wiring concerns; solenoid electrically or hydraulically stuck on.

Shift Concerns: No 2-3 Shift (Automatic)

HYDRAULIC/MECHANICAL ROUTINE

• Bolts not tightened to specification

• Retighten bolts to specification.

• Gaskets damaged

• Inspect for damage and replace.

• SSA failure to operate in a normal manner

• Refer to Electrical Routine No. 221.

• Direct clutch accumulator regulator valve, 2-3 shift valve, springs — stuck, missing, damaged, misassembled

• Inspect for damage. Repair/replace as required.

 

They haven't chased me out of here yet.

I'm going to tear this post apart. No offense intended, but there is so much wrong that I can't just leave it here without commenting.

There is no tow mode in a 2000 model year truck. The first year for that was 2003, and that was only in the 6.0L diesel. Gas trucks started to get it in 2005. Your truck has overdrive off, which functions very differently than tow/haul.

When you have OD OFF (what you're calling tow mode) the trans will not shift to fourth gear, which is overdrive.

That's why it is still trying to shift to the non existant third gear. If it hasn't set a code it won't know that third gear doesn't exist. And if third gear doesn't exist, fourth gear (OD) is impossible.

A stuck valve can't cause this. If the 2-3 shift valve were stuck it would stay in second gear and never try for third. It is trying for third, but there is nothing there.
To make the 2-3 shift the ONLY thing that happens is that the direct clutch applies. The direct clutch makes third gear. The intermediate clutch makes second gear.
To shift from 3-4 all that happens is that the overdrive clutch is applied. The torque converter clutch is not involved in ANY shift. The torque converter clutch is applied independent of shifting. It has nothing to do with changing gears.

The intermediate makes second, and stays applied for third. Your direct clutch is gone.

A solenoid can't cause this just like a stuck valve can't cause this.

I'm sorry to have to tell you that this trans is done. It needs to be rebuilt or replaced. And hard parts are going to have to be changed, too.

 

First of all thank you RovinBones and Mark for the input. Very much appreciated. 2nd, no offense whatsoever! I’ve been wrong plenty of times and will continue to be in the foreseeable future.

When a problem like this happens nowadays the first response is to scour the internerd for information and sometimes that info is flawed and leads to a misunderstanding of how a system works. The transmission has just been a black box until yesterday when it failed so I’m playing the student role trying to understand it so please excuse my ignorance.

Also, I am in no way arguing or trying to disagree with anything said here I’m just trying to understand the logic and mechanics of the system and its controls electrically and mechanically.
That being said, a few questions/statements:

Mark, Yes there is no tow mode. I understand it is just an overdrive lockout that is on the shifter stalk. It just says overdrive on the light. My 14 expedition has a tow mode that alters the shifting and coasting in a true “tow” mode. I was just using the term generically because I use that function when I do tow because I do know the overdrive is weak in this particular flavor of 4r100.

Question 1: When in Drive with overdrive enabled (not locked out) my transmission try’s for 3rd gear but, as stated, it runs away when 3rd is commanded. So if this is true, why when OD is locked out does it not try to shift to third? There is no code for the system to associate not shifting into 3rd so, why doesn’t it even try? 3rd is not inhibited normally when OD is locked out.

Question 2: What all causes the Direct Clutch to engage? Is it a function of SSA turning off only? Mechanically what happens?

Question 3: I know there are steels and frictions in the direct clutch but is there a sprag associated with this drum as well? The reason I ask is because there was no slipping or softness to the 3rd shift prior to it just “going away” all at once. Based on the weird clunk/double bump when it happened, that tells me something failed directly as opposed to “wearing down” over time.

Question 4: I guess this comes from my previous question. When you say “Hard Parts” will need to be replaced in the direct clutch, what in your mind was the failure? Sprag, Seal, snap ring coming out of grove? I guess what I’m asking is what parts in a standard “deluxe” rebuild kit would not be included to be replaced during the rebuild?
Question 5: There have been several articles and tech pubs that I have read that show the Direct Clutch being used for reverse as well as 3rd and 4th so if mine is toast why is Reverse working?

Mark is there something wrong with this for the mechanical logic table for clutch packs and sprags? I don’t see a sprag for the Direct Clutch and it shows intermediate clutch being used for 2nd 3rd and 4th.


Thanks in advance for the online education. You guys are great and very patient with shade tree clowns like me. I’ve rebuilt from the ground up a couple of 4x4 jeeps and my notch mustang but, until yesterday, the transmissions have always been plug and play.

 

As an observer, and one accumulating knowledge of this transmission model, I thank you for adding to what little I currently know.