Goofy shifting transmission

[jlbota]

I have an 03 2500 with the 48RE and noticed it seemed to be shifting way to fast into lockup. Basically if you give it all she's got it will just completly shift through all the gears and won't hold any RPM's. So I went to my dealer today and me and the transmission guy took mine for a spin and then an 04 with the same setup. And the 04 shifted well and held its RPM's through every gear. So my question is this... Has anyone else experienced this? The transmission guy seemed to think maybe there might be an update for the PCM but wasn't sure until we got it hooked up. Just wanted some input. He said there was definitly a difference between the two and I wasn't just being paranoid. Any info is appreciated.



I have also noticed on back roads that it doesn't downshift properly and seems to lug alot unless I shut off overdrive and really give it some pedal.

 

[jlbota]

Wow. . No one has this problem? Or has any idea whats up?

 

[rbattelle]

It's an interesting problem, and probably lies in software (as opposed to hardware problems with the transmission). But I can say it's one I've never heard of before. Could it be as simple as a bad connector at the T/C lockup solenoid?



Here's one test you can do. The 48re is programmed not to enter O/D untill the fluid warms up (I forgot the exact value). So if everything is working, on a cold morning startup if you can manage to accelerate up past 45 MPH before the transmission warms up, it should refuse to enter O/D. If it doesn't, that could indicate a problem.



I think probably you didn't get a lot of responses because no one else seems to have experienced this... yet.

 

[Bertram65]

Are you saying the trans will not go into overdrive if you go over 47 or 48 MPH if it is not warmed up? I can be on the highway almost instantly from my house and the trans shifts into overdrive every time at 47 or 48 MPH, even on the coldest mornings, it has done this for the last 10K miles.

 

[PSAJB1]

I have the same setup as you accept mine is a 3500. My trans shifts the same way yours does. The most I can get is 48 mph at 4th lockup. I thought that that was just the way the trans shifts from reading what others were posting over the past year or so. I just got mine back from the dealer yesterday for the two recalls and while it was their I told them that the trans got weird on me once in awhile after the use of the OD lockout. The trans would shift weird while taking off it would shift 1st then go to 2nd to 4th lockup back to 3rd lockup back to 4th lockup. The trans guy test drove it along with the shop supervisor and said trans shifted normally. I have not had a chance to pull with the truck since I got it at the end of 10/03. I figured maybe with a load from my TT it might hold gears longer. The truck only has 4500 miles on it so I have a long way to go with the warranty if their is a problem. Let me know what the out come is your dealer might be better then mine.

 

[jlbota]

Super shifter!

I guess the real problem is that it seems to not hold RPM's. Now if I take off normal it will hold RPM's through every gear like it supposed to .

But if you really give it the go pedal it just can't seem to get into the last gear fast enough . It seems like once you reach that above 45mph mark it just wants to stay in OD and no matter how far you push the pedal it doesn't want to downshift ... It just kinda lugs along. Even if if I shut OD off it kinda lugs in 3rd also.

If I gave the 04 the pedal it would downshift without much trouble at all even when I laid into it. That truck would just GO.

Mine just seems to not downshift properly like it should. It kinda acts like an old transmission without a kickdown cable hooked up.

 

[rbattelle]

If this were an old transmission, I'd say your kickdown cable was borken/maladjusted. I don't think there is a kickdown cable on these trucks (or diesels in general?). Still sounds like a software glitch preventing kickdown.



I will check my powertrain diagnostics manual when I get home to confirm about the O/D lockout on cold days.

 

[jlbota]

I know it doesn't have a kickdown... I was just saying thats what it acts like.

 

[Bertram65]

Same here on the kickdown, over 50 MPH it will not kickdown no matter what. It will however hold 3rd if I am on the pedal hard from a stop or lower speed, in fact I have had to let off a little so it will go into OD.

 

[rbattelle]

As an aside, I looked in my PDM this morning. It says on page 9:



1. If transmission temp is below 59 degrees, it won't go into O/D.

2. If transmission temp is below 69 degrees, torque converter won't lockup.

3. If transmission temp is above 275 degrees, it won't go into O/D. Furthermore, if it's already in O/D when it hits 275, it will downshift to 3rd and refuse to go back to O/D until the temp drops below 240 degrees.



If you can't convince your dealer that there's a problem with kickdown, I don't know what you should do...