First thing I'm going to tell you is not to tow in 4th gear. Now if you have a delayed 4th gear engagement it could be because of the 3-4 Accumulator spring in the valve body, these springs are commonly found broken, even mine was broken in 3 pieces.I'm new to this forum...not new to dodge diesel, but my previous experience has been with manual transmission. My truck has 195K miles, of which I had logged the last 25K....use it mostly to pull a 5th wheel camper. The only mods from stock are no cat converter and an after market breather
My 48re exibits these problems...
1) While NOT towing, transmission shifts normally(except for 2 below) all the way to 4th gear. Then, it is as if it shifts to neutral/4th gear, mostly neutral(Tow/haul button has no effect). Pull shift lever down, symptom goes away. It only does this VERY OCCATIONALLY, but enough that I'm worried about hooking to my camper and getting away from home. If TOWING, does really strange things in the mountains. My camper weighs maybe 10K, normally pulls it like it isn't back there(except for the fuel milage). As soon as the engine temp get above normal, the t'mission acts as though it has no idea which gear to get into(manually downshifting resolves SOME of the anomilies).
2)OCCATIONAL HUNTING between 1st & 2nd at very light throttle...I think I've seen some suggesting that this synptom is related to the pressure solenoid & switch.
Any help would be appreciated!!!
Now if you're having 1-2 shift issues check out having the kickdown band adjusted, if you tow you have to adjust the band much more often then regular usage.
Worst of the worst you need a rebuild but they're cheap and easy to rebuild and FUN!
To be honest, I made a pledge that every vehicle I buy that is high mileage that I would rebuild the transmission. (Yes sounds nuts but sets my mind at ease, especially when I tow)
I rebuild these and they're operation is simple. Try to accumulate as many miles as you can on these transmissions before they age, As they age the seals harden and it's just horrible when they do. If you rebuild a transmission you can certainly feel a difference in the shift of one that has new seals versus old seals. Much firmer shift! After I rebuild mine I had a joygasm because that thing shifted like a dream and it was so dam fast, of course I upgraded the rear planet to a 6 Pinion and used alto red's and alto kolenes, I also have a 3 row all aluminum radiator and a external transmission cooler so everything runs ice cold. I must say luck is on my side because when I replaced my rear planet it decreased the total end play from .082 to .06 so it's on the money.
Anyways seems I wrote a novel. Any other questions I'm here!