question about 48RE shift logic

[E7mack96]

OK, i am trying to figure out if I have a problem with this 48RE.



Can one of you tell me the sequence of events that must occur to get the trans to lock the converter in 3rd gear.



I drive with a light foot and i get this:



take off in first, and within a few mph, it shifts then shifts again sometimes, almost immediately, which i assume puts me into 3rd. As i am slowly accelerating, it stays in 3rd until about 45, then goes into 4th. at 50 the converter locks firmly. It will stay locked unless i drop below 45.



Sometimes, i feel the converter lock in 3rd (firmly, like the 4th gear lockup), around 35 or so and then speeds increase slowly until I am cruising at about 40 at 1300ish rpms.



I would like for the converter to lock in 3rd all the time, because otherwize the trans is revving to 1800-2000 in 3rd and slowly accelerating (due to my light foot, not excessive slip) to 45 until 4th gear kicks in.



So, Is third supposed to lock the converter? and at what parameters being met?



Does 2nd ever lock the converter? under what conditions if so?



Why does the indicator on the column not show 1st gear light up if you try to select it?



Does the trick to lock the converter at will (from the 47re? i had in 1999) work to lock the converter in the 48re, without codes?



I am clueless to autos, please educate me.



Tony

 

[JLandry]

Tony,



There's no exact shift behavior as it depends on many factors. Detailed descriptions of shift behavior can be found in the transmission section of the Dodge Service Manual for your truck.



Are you sure the differences you've experienced in shifting isn't related to transmission temperature?



The torque converter clutch will only activated in 3rd gear when the transmission is warm and when cruising on level terrain (i. e. : a low load on the transmission).



Best regards,



John L.

 

[BGlidewell]

I THINK what you are describing is a common problem for these caused by a bad electronic module inside the transmission. I did a search on this a long while back and IIRC it was around $170 part and a drop of the pan to replace. I'll see if I can dig up the actual part nomenclature...

 

[BGlidewell]

https://www.turbodieselregister.com...missions-2003-2007/198630-1-2-shift-hunt.html



FWIW...

 

[DaveHess]

Mine can't decide between 3rd and 4th and if it should lock-up the converter or not on a slight grade under light throttle. Mother Mopar blamed my light throttle driving behavior for the 48RE's indecisiveness. So now I'm saving for a trip to Dave Goerends! That'll fix it. Forever.

 

[PGreenleaf]

The tow haul mode on the newer 48re ( starting in the 05s ) eliminate most of your complaints. Remember although it doesnt pertain to you, that the towhaul on the 04. 5 isnt a towhaul ,its a overdrive lockout same as you got. Dash wording is different. Starting in 06 the 48re is the best setup . Has 3 setings ,( normal,towhaul, and OD lockout. ) On this trans you can get lockup in 2nd if you shift to 2nd manualy.

 

[cerberusiam]

OK, i am trying to figure out if I have a problem with this 48RE.



Can one of you tell me the sequence of events that must occur to get the trans to lock the converter in 3rd gear.



I drive with a light foot and i get this:



take off in first, and within a few mph, it shifts then shifts again sometimes, almost immediately, which i assume puts me into 3rd. As i am slowly accelerating, it stays in 3rd until about 45, then goes into 4th. at 50 the converter locks firmly. It will stay locked unless i drop below 45.



Sometimes, i feel the converter lock in 3rd (firmly, like the 4th gear lockup), around 35 or so and then speeds increase slowly until I am cruising at about 40 at 1300ish rpms.



I would like for the converter to lock in 3rd all the time, because otherwize the trans is revving to 1800-2000 in 3rd and slowly accelerating (due to my light foot, not excessive slip) to 45 until 4th gear kicks in.



So, Is third supposed to lock the converter? and at what parameters being met?



Does 2nd ever lock the converter? under what conditions if so?



Why does the indicator on the column not show 1st gear light up if you try to select it?



Does the trick to lock the converter at will (from the 47re? i had in 1999) work to lock the converter in the 48re, without codes?



I am clueless to autos, please educate me.



Tony

First of all, its stack shifting into drive. This could be several things but the most common is you need to tighten up the TV cable a bit. This will allow more throttle valve pressure and require more wheel speed to get the governor pressure up to overcome it and shift. It should stretch your shift points out a bit under light throttle to stop the funny stuff. It will however hold a gear longe runder hard acceleration and you may have to lift to get OD. Its abalance between how you drive most of the time and the functionality you want so adjust and try it till it works like you want. If that doesn't help or you start gettting shuttle shift a gov solenoid and transducer is the next step.



It SHOULD lock in drive under normal driving and that will depend on throttle position, wheel speed and TV pressure. Again, adjust the TV cable and see if that helps.



2nd gear should lock if you manually shift it into second. It does on the later ones so try thta and see what you get. It generally won't lock in second when in drive unless you mod the VB, increase pressures, etc.



If the indicator does not show 1st either the range selector is misaligned or bad, the shift cable is misadjusted, or there is a linkage problem on the VB. Start with the easy stuff first as the range selector is a bit finicky on position and sometimes it just takes minor tweaking.



The TC lockup switch will generally throw codes unless you wire a resistor into the circuit on a 3rd gen, thne they work the same as your 99. However, it will stack shift the trans into OD unless you have a lot of throttle into it.



If you want to materially change the way the lockup works you will need a controller. Not much you can do with the stock program. A good TC is most times a much bette rionvestment.

 

[E7mack96]

update:



I was off work today and crawled under the truck. The reason the shifts were stacked, ect. . was that the kickdown cable (what is the proper term for it these days?) was disconnected. It appears that whomever worked on it last had installed it wrong and didn't have it fully seated on the shaft with the keyway engaged. It was all rusty and just laying there. I got it back on and now the trans shifts great.



Is there an adjustment for this kickdown cable? I could not find an adjustment location at either end.



Third still is not locking up like I think it should. It does lock sometimes, but I haven't been able to get a rhyme or reason to the logic for it. Hence the question of a possibility of adjusting the kickdown cable.



Thanks again,



Tony

 

[Matt400]

On the 03 I had the only way I ever saw D locked under acceleration was to select "OD off" and then getting more agressive into the pedal would lock it.

With "OD on" and a light pedal it would go through all the gears up to 4th and then only lock once you were doing 50 or better for 4th locked. Sometimes a relase of the pedal was required to get the lock up if you were not easy enough on the pedal such as climbing a hill.



I don't think the oem software will normally allow for D locked with the OD button "on" unless there is some other condition like temperature being too high in which case it will lock the TC and at the same time lock out OD for you without hitting the button.



I think what you are looking for is. . shifts like- 3rd, followed by TC locked, then 4th, follwed by TC locked but that would require the TC to be unlocked and relocked + under light pedal conditions 3rd locked gives pretty close to the same RPM's as 4th unlocked.



I didn't like the shift stratigy on my 03 much, later I bought an 05 which is all by istelf and was happy for several years untill I doubled my towing weight and added an E Brake then the 05's stratigy was no good for me.

The fix for me was to flash it back to the way the 03 worked and then add a BD TowLoc which gave me programable set points for my TC and EB.

 

[E7mack96]

ok, the new thing is that when coasting to a stop, at about 15 mph, you can feel the transmission kick into first. It is almost like you pulled the lever into first. It causes a pretty mild jerk. it that normal?



Otherwise, it shifts up fine, but does not downshift often when punching it.



The kickdown cable slides in the braket as you press the pedal, and the actual wire starts pulling out about 1/2 of pedal.



I really need to find one that is working properly to compare with. Anyone in Gainesville with an 03-04 cummins 48re?

 

[Matt400]

May or may not be but. . it is a possibility the throttle valve is sticking, might be the reason someone left the cable disconnected trying to not agrivate things. You find it and connect it back up and now have a new fault.



Too low TV pressure can give the over sensitive downshift, too high TV pressure could cause kick down trouble.

Sonnax makes a repair kit to restore this trouble "if thats what you have"

Check it out here. Click on the instructions in that link and you can read all about it.



Before doing all that I would make extra sure the cable itself is not hanging up.

 

[cerberusiam]

ok, the new thing is that when coasting to a stop, at about 15 mph, you can feel the transmission kick into first. It is almost like you pulled the lever into first. It causes a pretty mild jerk. it that normal?



Otherwise, it shifts up fine, but does not downshift often when punching it.



The kickdown cable slides in the braket as you press the pedal, and the actual wire starts pulling out about 1/2 of pedal.



I really need to find one that is working properly to compare with. Anyone in Gainesville with an 03-04 cummins 48re?

The down shift to first is pretty normal. Usually with a stock trans you don't feel it unless you put a lot of TV pressure into it, but, things vary between units.



The kickdown cable housing should NOT slide in the bracket, it should be anchored solidly at both ends with the cable the only things that moves. To adjust you shorten or lengthen the cable houisng via clips at the connection to the APPS.



If its not downshifting that would make sense as it can't get enough TV pressure to force the shift, yet at light throttle there is probably enough to feel the downshift to 1st at a stop.

 

[E7mack96]

Also, it is defineatly locking in third sometimes, usually under light cruise, and then when it shifts to forth while locked, it releases the lockup about 1/4 to 1/2 second later then re-engages lockup at about 50.



As for the tv cable, yeah the square housing part of the cable slides in the bracket about 1 inch, then starts pulling the cable out, about 3/4 inch under full pedal (watched while wifey slowly pressed accelerator a few times) I see the white thing i assume is a clip, and will see how it comes apart.



As a side note, on the first trip to Ohio and back, i was pulling a trailer about 3k in weight and about 3K in the bed too. On some hills on I-75 in KY, the truck converter was slipping from about 1600 rpms up to 1900. The road speed stayed the same. It did this 3 times. I did slow down to make sure i didn't burn it up. Could this be due to that cable being disconnected? is the strength of the converter lock controlled in some way by that valve?

 

[cerberusiam]

As a side note, on the first trip to Ohio and back, i was pulling a trailer about 3k in weight and about 3K in the bed too. On some hills on I-75 in KY, the truck converter was slipping from about 1600 rpms up to 1900. The road speed stayed the same. It did this 3 times. I did slow down to make sure i didn't burn it up. Could this be due to that cable being disconnected? is the strength of the converter lock controlled in some way by that valve?

If the TV cable is not hooked up on these transmissions you will burn up the trans with the lack TV pressure control. Yes, that cable not working correctly is the problem and you already have some damage at this point.

 

[E7mack96]

another update

OK, last week, I unhooked the TV cable from the accelerator and removed the cable from the housing it attaches to. Sure enough, there was a clip the locks the cable into place. (I couldn't see this clip it with it hooked up). It was not pushed in, locking the cable. After eexamining the arrangement, I installed the clip with just a little slack at the cable end. The downshift into 1st is barely noticable now. I would call it the proper way it should work. I don't even notice a downshift into second at all.



What is messed up is the the previous owner had all the work done at Dodge and it seems to me that the guy that worked on the transmission was more clueless that myself.



Now on to my next project : "Lack of rear parking brakes shoes installed after dodge dealer replaced disc pads" or possibly : "pass side tie rod end about to fall off and I need to fix that soon"



Thanks for all of everyones help in this transmission thread.



Tony