Having an issue with an E-350 SD transmission. It's a 4R75E, AC2P-DA. I know this forum is supposed to be for vans up to 2013, this is a 2014 (99% same truck).
The problem is the dreaded "No Overdrive". This is a commercial unit, used to haul passengers on a fixed freeway route. Never used for towing or other heavy work. It has the 5.4 V8 and 328k on the clock. Original trans got serviced per Ford's schedule with fluid and filter changes every 50k using full synthetic fluid.
Original unit failed, no OD, just like putting it in neutral, revs freely. Boss didn't want to go the route of a new Ford unit like we usually do. Pulled the pan & valve body. Found very small amount of residue on the pan magnet. Found the OD servo intact and the retaining ring also intact. Removed the transmission, had replacement from a national chain wrecking yard deliver its replacement. Put that one in it, no problems, pulled THAT pan. The fluid showed ready for a change but no burnt look or smell, and installed a new filter. Refilled the transmission with proper fluid, adjusted the range selector, took it for a ride and, son of a gun. Same dang problem. No OD, revs freely. Turning off OD with button and the trans shifts 1-2-3 and runs and drives normally.

Only fuse I can find is the one for the OD button, it's fine.

Is this a slightly comical coincidence or am I missing something?

 

Someone said the wire in the column from your OD button can break, I've not experienced it, but worry now as my van is old.

 

Improve the name of your thread and post these symptoms in the Transmissions sub-forums. Thread title should reflect something about the problems you're trying to diagnose and/or repair.

 

Does the Overdrive Light blink or is the wrench symbol showing in the dash?

I unterstand you have zero codes, no flashing icons or codes or the OD light but can't use OD, even after trying to push the button on the stalk.

Honestly sounds more like an electrical short to me, just like the circuit to the PCM or the control button is fried.

Edit: just came across this video. Did you try that?

 

While that is true, the button in this van works as it is supposed too, proving it isn't that wire/circuit.

 

Then it's probably due the old/worn ***** (I wish I'd get a Dollar everytime I hear that 😁 ) preventing the fluid pressure to full engage the solenoid or the Snap Ring broken up clogging the solenoid Cylinder seal in the Shifter Box, as shown in the video.

Big plus: you get more of that nice V8 sound keeping the
shifter on the non-od position
​​​​​​​Cons: but only until the tranny tries to switch to 4th

 

Update: Had the valve body out and checked it over. All of the valves operate freely with no sticking. All eight checkballs were there, the same size and appeared undamaged. I cleaned the valve body with brake clean and again verified the valves move freely. There were no bits and pieces of clutch or metal or other junk clogging anything.

The snap ring for the OD servo was intact and in place. I took the OD servo out and closely inspected it. Found slight damage to the upper part of the seal. The band was visible through the hold next to the servo, a finger was able to move the band probably a quarter of an inch. I was able to "apply" the band with a small screwdriver through the hold that the servo goes into. It tightened the part visible through the hold next to the servo bore. Replaced the servo itself with a new Ford part and installed a new snap ring. I pressed the servo into its bore and watched the band move and tighten.

I replaced the check ***** into their respective holes and reassembled the valve body, reinstalled the valve body, the wiring and refilled with Merc LV. Went for a ride and found no change in behavior what so ever. Still no overdrive, revs like neutral. Turning Overdrive off using the button on the shifter and I get a great shifting three-speed transmission. With that button pushed in (OD off) it up-shifts fine and has engine braking in 1st, 2nd and 3rd. Ready to yank the damn thing and just put a Ford reman unit in it.

Before I spend $2,500 MORE of my boss's money, does anyone have any other ideas?

 

Well....if its YOUR BOSSES MONEY!!!!...

 

You can choose to continually chasing an issue you're so far unable to diagnose and/or repair OR bite the bullet and install a known working part with warranty. If time isn't an issue keep on chasing the problem.

 

Yes, use the Ford IDS software and shop manual and go through every step in the transmission diagnostics.

 

It's going to get replaced with a reman from Ford.