545rfe Won’t Stay in 4th Gear

[NoonAm]

2005 Ram 5.7 w/ 545RFE
I had major slipping and engagement issues with my previous transmission so I replaced it with a used unit with 150k miles.

My current (and previous) transmission would shift from 3rd to 4th, then prematurely shift into 5th. I have to lug the engine in 5th to shift down, which jumps back to 3rd then to 4th with an early shift to 5th. This is annoying while driving on highways with any grade.

I noticed that the transmission will stay in 4th when the engine is cold. Not sure if this is related. I know 4th is there as there’s no slipping, but it doesn’t like sticking around long enough to make an efficient shift into 5th and requires too much throttle to shift down from 5th (skips 4th) and screams in 3rd.

I’ve replaced the filters and fluid.
No check engine light

Any help is appreciated!

 

[NoonAm]

FYI- my slipping issues were solved with the new transmission. However, the 4th gear issue is still there making me think it’s a TCM malfunction.

 

[rzr6-4]

What size tires do you have? Mine does a similar thing and I think that it goes to 5th thinking all will be fine but then it doesn't have the torque that it thinks it will (from old age, tire size, etc) and starts to bog. Mine will do the same thing and after slowing a few mph it will drop to 3rd. Mine has always done it some but after getting my larger tires it got noticeably worse.

I spend most of my time in tow/haul. It makes it think twice before going to 5th and depending on the road and speed I will spend a fair amount of time in 4th when doing that.

 

[jws123]

Most rams will not go into Overdrive until it warms up a little bit depends on the temps outside its normal as long as your not actually Starting in 4th gear

 

[HemiLonestar]

Tran will not go past 3rd until it is up to temp (both 4th & 5th are overdrive ratios).