No 2-3 upshift PO 750 code 4R100 Tranny

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I have a 98 Expedition 5.4 4x4 with 4R100 Transmission About 200K miles.
Problem is unit wont shift out of 2nd into 3rd or 4th. Started as an intermittent problem where it would erratically shift from 2-3 to OD, then it would work fine at speeds below 55 mph, then it would not shift out of 2 at all, but when I went over manhole cover bump, it would shift out of 2, only for a short period of time.
I have a 750 code and a 741 code.
Mechanic wants to sell me a new transmission. Says there is a short in solenoid pack. I have also heard that 2-3 upshift valve gets stuck.
Anyone had this problem, or can make a recommendation other than a new or rebuilt tranny?
 
Check the shifter position switch, whatever it's called. It's a potentiometer that goes kablooey.

A fancy scan tool will tell you what the computer thinks the trans is in vs what you selected.
 
Look into Seafoam Transtune. You may have some blockage that can be dislodged with a solvent. Disclaimer: use at your own risk.
 
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Like stated, you probably have a solenoid issue. With 200k miles, you would have a hard time finding someone to just replace a solenoid. A good shop would have to stand behind their work and wouldn't want to deal with an upset customer after his transmission failed shortly after doing a minor repair. You could try an additive such as Lubeguard Red or trans clean. You have nothing to lose at this point.
 
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Mechanic said he is going to replace shift solenoid A and B. Part was 200.00. He said they come in a 2 pack.
He said the error code was a short in solenoid A which was 1-2. A little confused since my main problem was in 2-3 shift range.)
He also wants to add a bottle of Lucas Transfix to help in the event of stuck valve(s.
Part of me wants to see if the new solenoids fix the problem first, but at 200k miles can it hurt to use this additive?
 
I question his addition of Lucas since there are better choices. I wouldn't add that thick stuff to my transmission. If it were me, I'd have him skip the Lucas.
 
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Originally Posted By: Fitz98
Mechanic said he is going to replace shift solenoid A and B. Part was 200.00. He said they come in a 2 pack.
He said the error code was a short in solenoid A which was 1-2. A little confused since my main problem was in 2-3 shift range.)
He also wants to add a bottle of Lucas Transfix to help in the event of stuck valve(s.
Part of me wants to see if the new solenoids fix the problem first, but at 200k miles can it hurt to use this additive?


If you don't want to go with a solvent like Seafoam Transtune, then go with Lubegard Red; it's known for freeing up stuck valve bodies, governors and solenoids. Also, a multitude of transmission shops recommend it. I have not heard of such recommendations for Lucas.
 
If you don't want to go with a solvent like Seafoam Transtune, then go with Lubegard Red; it's known for freeing up stuck valve bodies, governors and solenoids. Also, a multitude of transmission shops recommend it. I have not heard of such recommendations for Lucas. [/quote]

Good advice. I have used both with good results.
 
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Usually, a valve sticks because either the valve or bore are worn, or because a piece of debris (like a piece of snap ring broken off) is lodged in it's passage. No magic transmission repair in a bottle will fix of that for you.

I'd replace the solenoids and move on.
 
As Lubener stated in a previous post, mechanic did not want to invest into a new solenoid pack only. After he found out that the solenoid pack he got was the wrong one for this tranny. The one needed was 400.00 cost, not 200.00 and he feels that would be overinvesting into this transmission.
He said he took the original out and tapped on it to free up the valve which was confirmed as stuck open and now moves freely, then added the Lucas Transfix. I tried to intercept the addition of the transfix after reading these posts, but it's already done.
Personally, I would have liked to replace the failed part, since now if it was a broken snap ring or spring or other debris, that is now dislodged and possibly moving to other places.
He thinks the pump is going on it.
I will post update after I pick up the truck and drive it a while.
 
Sounds like you've found a good honest guy to work on your trans.
Rebuilt 4R100 is 1600 bucks exchange on Rockauto.
So that's a data point if yours fails and you're pondering replacement.
 
Latest report.
While filling tranny, the mechanic noticed a lot coming out on the floor. There was a large 1" long rust hole in the side of the filler tube. He did mention that he noticed some water in the pan. I would imagine driving through puddles, road water washup, etc may have gone through hole. I am no expert on hydraulics, but I would imagine that water contamination in the fluid may have contributed to loss of pump pressure. I am not sure how much water was in there.
Solenoid was stuck and he was able to free that up.
7 new quarts plus lucas transfix.
Wondering if it may be a good idea to have system flushed in the event that the rest of the system may have moisture in fluid?
All seems to be working fine at this point so far.
I am also concerned about the rust particles from the hole in the tube, but I would imagine the pan magnet and filter would catch that before it got into transmission body if it found its way into the pan.
 
I've seen a lot of things in 50 years of working on cars but that's a new one for me.
I'd say you're good to go and figure you changed most of the fluid.
 
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