Lock-up Question

[Hammer]

Ok Slushbox gang need some input here,,I got a friend with a 2000 2500 4x4 automatic with a problem that makes no sense to me,since I'm a stick man,,His truck has a early lockup problem he has been bothered with and can not seem to get a straight answer on it,,I drove it and when you roll it down the road it will shift as follows,,1-2-D,then lockup,then unlock,shift into O/D and lockup again,,While it is in D and locked up it will pull rpm as normal,then unlocks and shifts into o/d and locks up again,,TPS switch has been changed,all connections checked and has been reflashed by local Dodge dealer to eliminate it ,but ,to no avail,,O/D solenoid is the only piece that has not been changed by dealer,,It has correct factory trans fluid and has no added trans guages,,This is a bone stock truck with no mods at all,,I made a call to a good friend that works for another dealer and he informed me that on some of the mini-vans DC added that shift program to help with fuel milage and his thought was due to the 2000's noted fuel milage problem that this may be the case to him also,,I do not buy it nor does my friend,my thought here is maybe the reflash did not take hold or am I missing something here,,Truck is just out of the warranty milage and he is frustrated to say the least,,Any idea's gang,we did a search and came up with nothing any help is appreciated... Andy

 

[LSMITH]

Hammer, I have been told that is the way it is supposed to work. My 99 has never locked up in D unless OD was locked out however. I remember Bill K posting that the newer trannies lock in d, then unlock, shift to OD, then lock again. I could be mistaken, but that is the way I remember it. If I am incorrect I apologize.

 

[redneckdr]

lockup

i'm pretty sure mine does exactly the same. i'll watch again tomorrow. i'm under the impression it locks in third, then unlocks before shift to fourth, then locks up in fourth (overdrive. ). see sig.

 

[chuck3]

Lockup.

Yes that is the way my Y2K works allso, but the unlock before OD is a very short and quick one on my truck. What is this fuel milage problem? My truck gets 19 to 21mpg FRWY I don't consider that a problem.

 

[Slick]

Lock up

Hammer, I have a 2001. 5 and it does the same thing. Lock up in D and then unlock and then locks up in OD. I drove three other auto's (all 2001) before purchasing my truck and they all, if my memory serves me (!@#%*) correct, did the same thing.

 

[GDouglas]

Sounds like normal operation to me. All of the lockup transmissions that I have worked on are set up to unlock for a short moment during a shift and lock back in again after the shift is completed. If the converter clutch stayed locked during the shift, it would feel like powershifting a stick shift and might just bark the tires if the converter clutch could hold during the torque spike.



Don't worry, just normal operation.

 

[Rammin]

TC lockup

this has been around before. I have a 99 and I don't think the transmission hasent been changed any. I had the same lock up problem,there is a TSB 18-02-99. Had the dealer reflash the PMC walla no more problem.

 

[Hammer]

Thanks gang,,I'll be seeing him tommorrow and will relay the info and will make sure he joins our great group,,I've never encountered this since I only had two automatics,one a 92 and a 95,,The 95 I owned never did it(guess the earlier trucks did not have the problem) so I was out to lunch on it when he tried to explain it to me,,As for the fuel milage deal,I was told that the 2000 trucks were stopped in production early (both V10 and CTD's) due to a computer parameter problem that resulted in some getting very poor fuel milage(we also heard that production was shifted to the next years models early due to this),,The truck I asked you the question is an automatic 4x4 quad with 4. 10 limited slip,,Its fuel milage is dreadfull for a Cummins truck(averages between 12 -14 around town)and the pulling power with a trailer,well lets just say that the old saying"wouldn't pull a greasy string out of a goats rearend"is in order,,Shame of it is,this is not a bad looking truck and nicely optioned,but,I can guarentee if we can not help it owner will send it down the road,,Amazes me that DC and their dealers just want our money and not to help us much,BUT,thats another story for another place,,Thanks a million gang,I'll relay the info tommorrow... ... Andy

 

[LSMITH]

Hammer, have your friend take it to Cummins for the low power thing. I realize that he should not have to, but that might be his only alternative. It would pi$$ me off BAD if I had a truck under warranty that I paid to fix out of my own pocket, but it would certainly beat the bath he will take selling/trading the truck in this market.



Now that I have said that, does it pull OK in the 1-3 gears? If it pulls OK in 1-3 then there is a reflash that guys have had done to help the pulling power in OD. I don't know what the number is, but someone will chime in with it. Lots of guys have had it done and said it helped a lot. I am not sure it applies to the 00 models, but 01 for sure. The reflash for the pulling power in OD is a Dodge thing by the way. Cummins would probably not know about it. Hope this helps.

 

[Slick]

Lock up

Drove my daughters 01 2500 QC gasser today and it too did the 1-2-D-Lock out and then lock up in OD. However it did seem to do the unlock for a much shorter period of time than my diesel. I don't know if the auto trans is the same but it definitely did the lock out and lock up thing. I drove it just for the purpose of checking this out as I am wondering myself now. Just my tcw!!

 

[GLASMITHS]

TC Lockup

Slick --



I believe MDouglas hit the nail; it would be a very strong shift if it did not unlock



And Mr Hammer don't worry about us SLUSH BOX GANG too much; as the saying goes, only little boys play with sticks



george

 

[JohnE]

A side thought here. Check the <b>I</b>ntake <b>A</b>ir <b>T</b>emperature <b>S</b>ensor. A local here got significant results by correcting a bad system. Remeber, the IS series engines rely on the electronic inputs more than your conventioal gasser.



Have you run the truck pulling or hauling a good load? The trany may work diferent under loading other than your right foot.



Just brainstorming



-John

 

[Hammer]

Row row row my truck.....

Thanks my,well we won't go there,,Yes had a car on a trailer behind it today and its a dead fish as power goes,,Will pass the IAT sensor on to him to try,,transmission works the same no matter if its empty or got a trailer on it loaded,,Noticed today when he started it that cold its sending alot of raw fuel out(kinda like a properly valved truck tuned up on a cold morning),,Never noticed a stock 24 valver doing this and brought that to his attention,,One of these computer scooters with 4. 10 limited slip should be a missle from a stop and should have plenty of pulling power so something to me is amiss,,Going to keep searching,not giving the ship up yet... .

 

[Stefan Kondolay]

Hammer,



if you have any question feel free to give us a call at the shop (604-504-4002). We have run into just about every transmission situation that there is. If it's transmission related Bill can get to the bottom of it. I know that he loves challenges. Just say who you are so that we don't need to go over all that has already been discussed.



Bill isn't a good typer so it much easier for him on the phone.

 

[Hammer]

Thanks Stefan,,I'll get a chance this week to do that and appreciate the help(and some good natured ribbing),,Hope to get him fixed up... Andy

 

[pcarlson]

Hammer,



That's the powertrain program for the transmission to do the lockup in third then unlock and shift to OD and lock again. It does two things, increases fuel mileage and second it cuts down on some heat build up in the transmission. You can reflash till the cows come home but that is what the transmission is programmend to do.



For those of you who haven't rode in a Allison equiped Chevy(I'm embarrased to admit but its true) it does the same thing. The Allison is programmed to lock and unlock in 3rd, 4th and 5th but if you engage the tow/haul switch it locks and unlocks 2nd thru 5th. The Allison is programed like this for fuel and heat. That is why DC programmend the powertrain computer like this. I must say I wish I had that Allison behind my CTD.

 

[georgej]

Pcarlson



It's my understanding that our diesel brethern over at chevvyville are having teething problems concerning the allison transmission when towing! If you're climbing a slight incline or fighting a headwind, the transmission will start shifting down so that even though there is plenty of power to pull the load it will not stay in overdrive. Hence you're humming down the road at 3000 RPM getting 8 MPG! I like the way my 47re will let me use the Cummins torque to pull!





Georgej

 

[LSMITH]

Someone correct me if I am wrong, but the Allison in the new GM's has no lock in the TC. It rather uses a tight TC that depends on good fluid coupling to transfer the power. The programming on it uses different settings for the two modes. I will say that empty the fluid coupling is quite good on the Allison, and the shift programming empty is superb.

 

[GLASMITHS]

georgej:



I'm with you on the 47re. Most don't seem to like it; however, it beats the heck out of anything else I've owned. That is the major reason i am keeping my options open on replacement in the spring. I just don't want to think about up shifting to O/D at 2800 rpm. I never drive that fast



With the GV in o/d at 70mph it is right at 2050 rpm; and that is sweet for power and mpg.



LSMITH- No kidding. The DURAMAX drives good unloaded so we can name it GM's new street queen I am not being ugly On the other hand, my Dodge Ram 3500 drives like a truck and that is what I would expect. The wife has an 01 Caravan, when we want to go smooth. But that rinky-dink seat just kills me. I get lonesome for my Ram's leather seat, ect, ect.

How do you like your Rancho 9000s'?



thanks



george