Well, pretty sure I have the six speed, but let say whats happening first. At around 38-40 while trying to shift out around 1600 tranny seems to hunt from 3-5-4-5 then shifting into 6 around 50. I say hunting cause its a little hard to get the gear hunting figured out. I read the low speed shudder and that might fix it, but I am not sure. Then when the truck is in 4lo and I shift from D to R it shudders to the point that even the seats vibrate. Also, it feels like the brakes are not going to hold the truck. While pushing the brakes thinking they are not holding, it sounds like I am pumping the pedal as if I am bleeding the brakes. The shifting is intermittent, but the 4lo shudder is there and obvious. Any feedback would be great. By the way the truck only has 43800 on the OD, just bought it a month ago w/41500. Did notice the problem on test drive. May need bands adjusted?

 

it may feel like you have a 6 speed with all of the hunting, but Im pretty confident you dont unless you're rowing the gears and making it hunt - the 48re is a 4spd.
What I have noticed with my 48re is this:
if you put it in 2nd and drive up to about 25-30 the tq converter will lock up
OD off and drive up to 42-48 the tq converter will lock up
OD on and at 55 the tq converter will lock up, its not a silky smooth transition if your really on the go pedal.
As for the 4lo concern - that cummins has ALOT of tq, but the brakes should hold it w/o problem.
Probably not what you were looking for....but this is what I have seen.

 

I have had the same problem for over a year. Stock truck, light throttle, usually slight to moderate grade, 40 mph - the truck shuttles 3-4-3-4 or lock-unlock-lock-unlock (I don't know which). Very annoying, and probably not good for the trans/truck either. I tried a TS performance shift enhanser, tried insulating the alternator wires (old school lock up interference fix), but no change. I recall reading about a 3-4 shift solenoid, maybe they go bad like the 1-2, causing similar symptoms.

Any help on this issue would be greately appreciated!

- Jason

 

For those with problems with shuttling in and out of OD at 40 mph, thats the nature of the electronic control and kinda of a twilight zone for OD. Normally, if you engage TH it will get past this point and be much more definite when it shifts to OD. Otherwise, you might want to use the OD lockout feature until you get up to 55 mph or so. They react a lot better when locking out OD below 50 mph.

The shift enhancers can help this depending on other adjustments in your trans, but, you can't push it to far or you get some other weird behaviour on downshifts.The OD shift is pure cmputer control and is based on speed, gov pressure, APPS, and TV pressure. About all you can do is influence the TV pressure with an enhancer and make sure the gov pressure is solid by upgrading the solenoid.

 

Thanks for the replies first. I hate to be illiterate, but what does "influence the TV pressure with an enhancer and make sure the gov pressure is solid by upgrading the solenoid". I asked a dodge mechanic about this and he said he could probably have an updated flash done and that the bands do not need adjusting, but this was comming from the one who said that the rear passenger axle seal wasn't leaking until, I said I had the drum off and saw oil centifuged in the drum. Is there a seperate solenoid seperate from the 1-2 that can be changed to fix the 3-4?

Jmerola, you having the same shudder affect in 4Low?? Anybody?

 

Your not, I am just talking Tech and not realizing it sound slike gibberish to others.


Ok, TV pressure. In your truck the TV pressure which essentially influences the shift points is controlled by the TTVA motor. There are 2 algorithms of, TH and non-TH, in the ECU for ramping this pressure by speed and APPS position. If anything is slightly out of whack and not perfect you get shuttling and indecisions about what gear it wants. Reason I said try TH first and see if that makes a difference.

A shift enhancer will sit between the ECU and the TTVA motor and take care of ramping the pressure faster and sometimes solve the shuttle. It is really meant for removing TQ management like some programmers do but it works pretty well on the shuttle because of what it does.

This will work fairly well on 1-2 shuttle and the 3-4 indecision at low rpms. If you have 2-3 shuttle you need to check the band adjustment FIRST then play with other settings. The bands are set by a machine so verifying that is a good step.

The second piece of the shifting algorithms is the governor pressure. In a simplification, its a balance of TV pressure against gov pressure that sets the shift points. If one of those is too high\low or not steady you get shuttle shift, hang shifts, indecision, etc.

The OE gov solenoid is a POS, putting it nicely. It doesn't work as well as it could on stock pressures. BEFORE you chase ghosts, replace it with one of the aftermarket ones, check your band settings then see where you are at. Will save yourself a lot of $$ and annoyance up front.

What frequently happens is at around 40-42 mph and light throttle the ECU says go to OD and lock the TC. What happens is the TC locking will drop the rpms so low the speed drops a couple mph and drops the TV pressure. The ECU says its time to downshift by the input parameters then its back and forth in that area. The only way to stop it is lockout OD or speed up and things generally straighten out.

As I said before, the 3-4 shift\lock strategy is completely under computer control. All you can do to influence it is - TV pressure ramp and gov pressure stability. To do that its replace the gov solenoid, add a shift enhanser, and maybe toy with the line pressure and TV settings on the VB.

 

Mine would do the same thing 3-4 4-3... We have this 1-2 mile 8-10% winding road (35-40mph) going to the house. I tried it in TH same thing huntin for a gear. Tried it with OD off, a bit better but still that searching for the gear. One day I left the EB on TH off and bingo, didn't shift one time about 1500rpm. Maybe the EB on locks the TC?
What do you guys use climbing long 6-8% grades when towing? I always just leave it in the TH, should I be using the OD off. And no6ohno I took your advice and saved the money on the DD tranny pan. I would still like lower ATF numbers though.

 

Yes, the EB normally keeps the TC locked down to its cutoff speed so its function is enhanced.

I always use TH and never have problems even on long grades. I have never seen the temp get over 200 degrees with the TC locked in OD. I am sure there are situations where its possible to get into heating problems but you just have to drive around them. I added the BD lockout box to mine so now I can run the TH mode even in drive, THAT is going to be a big difference in lower speed operations. IIRC, in OD Off mode on the newer trucks it will not lockup as aggressive and that could cause some heat.

What are you seeing for temps that concern you? I noticed a nice drop with the TC upgrade and even more when I got rid of the drain back valve and upped the line pressures. Better flow thru the cooler really helps.

 

Since its stock I don't know the exact temp but the ATF isn't the bright red color I would like to see after 10k miles. That was one reason I wanted the DD pan, cooling, temp probe, and drain. I figure more ATF changes the better. I had it at the dealership for another issue at 39k miles and they thought I hadn't done the tranny service at the 30k.
After showing them the invoice they ask if it was all towing miles, which was not the case. I know pretty much nothing about trannys except my last 01 Dodge dumped at 80k, but it was chipped.
I'm not ready to have it dropped yet for the TC, but what is the "drain back valve and how do you up the line pressure".
Thanks for your time.

 

Don't worry too much about the color of the fluid, the dealer idiots should know this but it seems they are looking for ANY excuse. The fluid may not be bright red after 10k miles but that does not mean it is bad. The additives that give it the color change over time and loose the color to almost a neutral shade. As long as it doesn' turn brown and/or start having a definite burnt odor chances are it is fine.

You probably don't want to see your stock temps if you do much slow-n-go driving towing. They suck on an OEM trans but you can drive around them if you see they are getting out of hand. A gauge is a good investment to keep tabs on stuff and your dealer should applaud not hassle over it. Lockup is your friend, the more you can keep the TC locked the better off the trans will be, even if you have to manually downshift and run higher rpms for a bit.

The drain back valve is located in the top cooler line under the driver side battery. Its sole function is to help keep the TC from draining while sitting. Since the OE setup doesn't allow charging the TC in park they opted for a check ball to help that. All it does is block 50% of the flow thru the cooler and still doesn't help drain back if the internal seal in the TC fails.

Line pressures are adjusted on the VB, either by tightening the screw for some small adjustments or adding a shift kit that will replace the springs and allow much higher line pressures. This will help just about every aspect of the trans operation and frequently solve a lot of the problems the OP and others have listed. The faster and firmer the trans shifts the longer it will last and less flaky issues it exhibits.

 

What gov. solenoid is giving the best results, what kind of shift enhancer, and what line pressure and Transmission Valve settings on the Valve Body should it be set at or can it be set that easy by a driveway mechanic. I feel safe changing a plug and play solenoid switch, but the other...... I would have to have something to go by at least.

Hypethetically, if I do not perform the above mentioned and have the bands adjusted and a reflash with the latest software will the tranny life suffer the conseqences?

Any ideas on the 4LOW shudder, still no hits on that one?

 

I am using the DTT Shift Enhancer and it works well. Its updatable also if you change your build down the road.

Line pressure can be upped 3 lbs per turn of the set screw. Its on the sid eof the VB towards the front drivers side I believe. You can maybe get 3 turns before you run out of the threads. Stock line pressures are around 55 psi at idle and 140 max. Most shift kits take them 85 psi at idle and 190-200 max or more.

PATC markets a conversion piece using a GM solenoid that is working well and I believe DTT is selling the same item. Suncoast has one that use the solenoid off of the 68RFE that seems to work. Not sure on the life times of either of these but quite a few people are using them and getting excellent results.

Adjusting the bands and reflashing will SOMETIMES address the issues. I never had any luck with nor a lot of others. Some have had that help. Its about all you CAN do if warranty is an issue and your dealer is being a pain.

I would take yours in and have them relfash and adjust the bands to see if that helps. At least you would have that done under warranty. If there is still an issue replace the gov solenoid and see if that will solve it. After that its time to work the VB over with a shift kit and get it fixed right.

You REALLY need to get the trans working correctly before adding a shift enhancer or your just masking the problems. The trans will still fail if there are underlying issues the enhancer covers up. If you get it shifting good without the enhancer and your not running a programmer that is remving a lot of the TM then don't waste the $$ on it. Just drive and enjoy.

 

Appreciate the advise. It had a 1000 mile bumper-bumper warranty from the dealer after I bought it used, but that was up about 1500 miles ago. Still have the 100k cummins motor warranty, but out of drivetrain warranty I believe. My issues/complaints were noted in the first 800 so maybe I will have a leg to stand on. I will try the reflash and insist on the band adjustment and go from there. Do you think reflash and bands will solve the 4low shudder though or is that due to the 1-2 gov. solenoid?

 

It would not hurt to adjust both bands and and see what happens. I am still unclear exactly what the symptoms are with 4 lo problem. Does it only happen in reverse? Does it feel like reverse is slipping?

 

The solenoid has a TSB on it. See if the dealer will replace it under that.

This shudder you mention..... Either something is loose, like a trans mount, or you are feeling the axles bind in 4 low. I'd lean towards the latter.

If you turn at all in 4 low on a hard surface the truck is going to buck and shudder. Even if you have varying air pressures you will bind the axles.