2016 85k miles, transmission went out

[ManUpOrShutUp]

Who told you that?

I have a battery disconnect switch on mine that I routinely use when I drive my other vehicle to work and the Expy is not driven for a week or two.

The battery gets 100% disconnected regularly, to prevent parasitic drains. Zero problems thus far... I reconnect the negative cable when I'm ready to drive the Expy, start her up and it drives / shifts just fine.

Whenever the battery is disconnected, the vehicle has to relearn idle, fuel trims and shift strategy.

From the manual:

When the battery is disconnected or a new battery is installed, the
automatic transmission must relearn its shift strategy. As a result, the
transmission may have firm and/or soft shifts. This operation is
considered normal and will not affect function or durability of the
transmission. Over time, the adaptive learning process will fully update
transmission operation.

To account for customer driving habits and conditions, your automatic
transmission electronically controls the shift quality by using an adaptive
learning strategy. The adaptive learning strategy is maintained by power
from the battery. When the battery is disconnected or a new battery is
installed, the transmission must relearn its adaptive strategy. Optimal
shifting will resume within a few hundred miles (kilometers) of
operation.

 

[762mm]

^ Yep, even my '99 Explorer's tranny did that after a battery disconnect, but I would hardly call it "going nuts" to the point of the truck refusing to shift into gear.

All late 90's - onward cars and trucks with automatic transmissions have this feature to optimize fuel economy, nothing new there. It should not affect driveability unless something is wrong with the tranny, though.

 

[762mm]

You don’t think the throttle body would throw codes?

‘there was no check engine light on

By the way, did you hear a whining sound (like an electric motor burning out) when in gear before the transmission stopped shifting? I had this happen on my old Explorer... it was whining in gear for a few months (drive and reverse), then one day completely stopped responding to engine output and felt like it was in neutral in all gears...

It turned out that the electric ATF pump gave up the ghost inside the transmission and no longer pumped fluid, which caused the transmission to act like it was in neutral when in gear (you'd give it gas and the truck would just sit there). It cost me about $1200 to have that replaced at a transmission shop, including the tow truck charge. The tranny needed to be removed from the truck in order to swap out that pump.

Once the pump was changed, the transmission was good as new again.

 

[rjdelp7]

I own a 2011 Mustang GT, with a 6r80. The battery suddenly died and flat wouldn't start. I boosted it and it started. The transmission would not shift past 2nd and was banging gears hard. The car had only 3,100mi. I installed the new battery and it drove perfect. I can verify it shifts firm, very firm. My owners manual has the same warning, under 'battery'.

 

[and0r]

You don’t think the throttle body would throw codes?

‘there was no check engine light on

Absolutely. The throttle body sensor is the device which "throws codes". The sensor itself may be operational, meaning the circuit is functioning (no short, or missing ground). Though the sensor itself can be reporting a valid, but incorrect reading, causing the transmission to "think" wrongly.
You have to understand what an input shaft actually is. This is a solid, geared unit. Only real failure can come from stripped teeth. This is highly unlikely on the Expedition, and is something which is very easy to detect once the transmission is pulled apart. So, the best advice here would be to actually inspect the old shaft. Make sure you see them taking it out, these scam artist mechanics these days are quite funny and will pull every dirty trick in the book. You have every right to see the part immediately after it's pulled.

 

[JExpedition07]

I was told many transmission shops try to not diagnose broken in service transmissions anymore because it is safer to just sell a complete new transmission. They can be on the hook if they attempt to diagnose and fix a transmission and the new part doesn’t fix.

 

[CaptOchs]

That sucks. I had to replace a transmission for a Charger. I decided to go with a junkyard transmission primarily over cost. It was $650 and they pulled it. I could replace the transmission 3 times for the cost of a single remanufactured transmission. The junkyard transmission is a transmission that has never failed. The remanufactured transmission is a failed transmission that was been rebuilt. The junkyard one did come with a warranty too. I also bought custom transmission oil (QuantumBlue) blended with the correct modifiers and higher temperature tolerance. The older transmission was never as smooth as the new one.

So what caused the failure? We never figured that out. About 8-12 months prior I had taken it in for 100k maintenance. I did coolant and transmission oil change. They claimed they don't power-flush. They drop the pan and replace filter/fluid. I think they probably used the wrong fluids though. I can't prove it.

 

[5x10]

I went to see the dropped tranny

they just put it on the lift so it wasn’t fully disconnected
The mechanic is saying it broker in the transfer case or in the body of the tranny
I had to leave so I asked them to take a picture of the broker input shaft
He then said it might not appear broken as it might be broken in the body of the tyranny

 

[762mm]

^ Anything is possible, even when unlikely. Sometimes a hard metal part can be manufactured with an air bubble inside and snap off like a twig under load.

I would still seek a second opinion though... just to be safe. Installing a $5k rebuilt transmission generates a lot of revenue for these guys, so they might be a wee bit "biased", lol...

 

[TobyU]

That sucks. I had to replace a transmission for a Charger. I decided to go with a junkyard transmission primarily over cost. It was $650 and they pulled it. I could replace the transmission 3 times for the cost of a single remanufactured transmission. The junkyard transmission is a transmission that has never failed. The remanufactured transmission is a failed transmission that was been rebuilt. The junkyard one did come with a warranty too. I also bought custom transmission oil (QuantumBlue) blended with the correct modifiers and higher temperature tolerance. The older transmission was never as smooth as the new one.

So what caused the failure? We never figured that out. About 8-12 months prior I had taken it in for 100k maintenance. I did coolant and transmission oil change. They claimed they don't power-flush. They drop the pan and replace filter/fluid. I think they probably used the wrong fluids though. I can't prove it.

We can only keep on preaching to to the ones that won't listen. You could change it three or four times before you ended up spending the money they want to rebuild yours or put a new one in. So the odds are always in your favor putting a good used one in.