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2001 T&C LXi 3.8l - 2003 GC Sport 3.8l
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Discussion Starter · #1 ·
My 2001 Town and Country shifted to 2nd too soon at light throttle, even shuddering the clutch pack a couple of times in very hot weather. Shift was firm but seemed like not enough pump pressure at that low RPM to sufficiently hold the clutch apply piston. I finally changed to Dexron 3 and that smoothed the shift out and it has not shuddered since then,15k miles.
I just bought a 2003 Grand Caravan 119k miles, with a similar issue. The seller said the trans was recently serviced but wasn't sure what fluid was used. I'm thinking I may need to change this fluid to Dexron 3 also along with a Dorman pan with drain plug (Part #265-832) like I installed on my 2001. I won't get all of the fluid out of the converter with one change so the drain plug will allow me to change whats in the pan a couple of more times easily until I get the old fluid out (or at least well diluted).
Any thoughts, direction, experience with this would be appreciated?
 

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The no brainer is Mopar ATF+4, I suppose.


Pennzoil Platinum ATF+4 - Pour Point: -48C
"due to Group II+/Group III base stocks used"

Valvoline ATF+4 - Pour point: -48C
"Valvoline ATF +4 is the full-synthetic automatic transmission fluid"

Mobil ATF+4 - Pour Point: -50C Mobil Semi-Synthetic ATF+4 ???

Havoline ATF+4 - Pour Point: - 51C

Petro-Canada ATF+4 - Pour Point: -51C
Formulated using 100% PURITY™ VHVI Synthetic Base Fluids and a unique additive system

If Pour Points are any indication of synthetic oil content, they all beat 5W-30 synthetic motor oil at around -42C.
Mobil 1 5W-30 Advanced Full Synthetic Motor Oil - Pour Point: -42C
 

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Discussion Starter · #4 · (Edited)
Thank you both for your information. I ran ATF+4 non-synthetic in my 2001 when I had the shift issues so It looks like I'll be trying Valvoline ATF+4 Full Synthetic. Price is not an issue. Maybe the full synthetic qualities will give me the shift quality I'm looking for.
Jeepman, in your first link under additives, David Castater noted:
"My local AAMCO manager changed the oil and filter, added a"friction modifier", and reprogrammed the computer. No problems since".
This brings up another question about reprogramming. The 'Daimler Chrysler Authorized Modification' sticker under the hood does not list any modifications. Is there a transmission reprogram modification that would benefit me that wasn't done with the previous owner? The only transmission related TSB I could find with Alldata is Number: 18-023-04
Engine/Transmission Controls - Surge After A/T Lock-Up. Could this program update possibly help my 1-2 shift shudder?
 

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as far as i'm concerned, atf+4 is atf+4, it shouldn't matter what sticker is on the bottle

pretty sure there's no such "reprogramming" by AAMCO either, there's very few things you'd mess around with in the TCM with the appropriate scanners other than clearing clutch volumes for a new transmission

i see many with the 1-2 bump or shudder, mine is the exact same with a new transmission and even with a different TCM

in my opinion the best remedy is to power through it, there's a feel to it and you can keep it smooth with the gas pedal by applying the right amount of power, it seems like the transmission shift logic gets poorer and poorer the slower you are, it likes distinct inputs and quick starts/stops

flashing a new firmware for the surge issue is likely not related to the 1-2 issue, it's more in the realm of the engine being too low in RPM, if i had to guess they're probably referring to the torque converter locking in 3rd and 4th
 

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A pan drop, fluid/filter change can cause the transmission to readjust to the new fluid. You can get a rough 2 to 1 downshift for up to 70 restarts. The reprogramming was likely setting it back to default settings so it wouldn't have the rough shifting. Most people don't bother with that though, and take maybe some rough downshifts for several restarts.

More on that here:

The designers of ATF+4 used synthetic blend base oil, the Group III oil giving the designers some better numbers. The Lubrizol additive was a game changer as well. The result was a synthetic blend which apparently some are using today, seemingly. The ratio, I don't know.

From the Center for Quality Assurance Web Site:
ATF+4® - What You Need to Know
In 2005, due to marketplace demands and evolving vehicle technology, FCA US LLC established a licensing program for its advanced synthetic Automatic Transmission Fluid - ATF+4. This program allows ATF+4 to be made available at retail outlets and through independent repair facilities for Chrysler®, Jeep®, RAM, and Dodge vehicle automatic transmissions. Click here to see all licensed brands.
They are calling it synthetic, whatever "synthetic means these days. It certainly isn't real synthetic Group Base IV oil.
 

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@mike5plus5
If you really put Dexron in your first van, I would immediately change it out to licensed ATF+4.
Three times.

If you’re not sure what ATF is in the second van it is a good idea to change it out. My advise is only to use licenced ATF+4 any of these will do.

Licensed Brands | FCA ATF+4® Licensing Program
 

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No, no, no Dexron ever!! We unknowingly did that to my mom's 94 Grand Voyager after rebuilding the transmission, because we didn't know back then that it took ATF+3 or +4. It lasted a few years, but the transmission ultimately ground itself up. There was so much friction material in the fluid that it plugged up the filter once, and the van would seem like it was in neutral until you let it sit for a while so the fluid would settle. Replaced the filter and fluid with ATF+4, but the damage was done and not much later the transmission gave a clunk and would barely move the van (binding up inside). It happened in town so my dad got it the few blocks home. Stripped the good parts from it and junked it. If only we'd have used the correct fluid...

I must drive my van hard enough that I never feel that shudder, even with 216,000 miles on the van. It's a 2004 though, so maybe the programming changed when they did the combined ECM/TCM into a single PCM.

Edit 10/8/22 - I've now noticed the bump/hiccup going from first to second gear under light throttle. So that's what you guys were talking about! :ROFLMAO: :p
 

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Discussion Starter · #9 ·
Thank you all for the education on AT fluids. Both vans now have ATF+4 and both have been drained refilled 3 times. That was a lot of $ for fluid but if it means the tranny will last longer then it's worth it.
Baron, I long ago formed the habit of using the throttle to get a good 1-2 shift but I can't always do so (like starting a turn through the turn lane with a slow-poke leading in front of me).
Another shift issue I've noticed with the 2003 van is when it shifts to 3rd gear the converter clutch applies almost instantly after the shift and the engagement is slow and brings the RPM way down (~ 2k rpm lower + the shift rpm drop), which lugs the motor. This is different than most converter lock-up sequences. Most of them usually wait to gain some ground speed after the shift before locking the converter. My 2001 T&C sequence does delay lock-up correctly like this. Would changing out the 2003 TCM for a 2001 part # help to alleviate this premature lock-up issue or is there other circuits in the 2003 tranny that would not work, or work correctly after doing this?
 

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Thank you all for the education on AT fluids. Both vans now have ATF+4 and both have been drained refilled 3 times. That was a lot of $ for fluid but if it means the tranny will last longer then it's worth it.
Baron, I long ago formed the habit of using the throttle to get a good 1-2 shift but I can't always do so (like starting a turn through the turn lane with a slow-poke leading in front of me).
Another shift issue I've noticed with the 2003 van is when it shifts to 3rd gear the converter clutch applies almost instantly after the shift and the engagement is slow and brings the RPM way down (~ 2k rpm lower + the shift rpm drop), which lugs the motor. This is different than most converter lock-up sequences. Most of them usually wait to gain some ground speed after the shift before locking the converter. My 2001 T&C sequence does delay lock-up correctly like this. Would changing out the 2003 TCM for a 2001 part # help to alleviate this premature lock-up issue or is there other circuits in the 2003 tranny that would not work, or work correctly after doing this?
The hard shift or the shift shudder typically is a result of a flaky shift solenoid or the flexing brass reed valves (aka clapper valves) it moves. There are threads here on this subject over the years. Either the solenoid from 1 to 2 is goofy or the valve it moves is messed up.

Just behind the battery and it's tray sits this Ultradrive shift solenoid pack assembly mounted to the top front of the transmission.

Font Auto part Metal Science Liquid


A look inside, notice a part is 'missing'. It fell off during vehicle assembly or later at a dealer or a garage. A reason why not to buy a rebuild kit and then install it blindly facing the transmission as these can fall out!

Circuit component Audio equipment Electronic component Hardware programmer Font



You can rebuild it and take a chance or just buy a new one from RockAuto. The most reliable in the after market is the Borg-Warner brand.

Automotive lighting Automotive tire Automotive design Automotive exterior Gadget


Font Automotive exterior Auto part Parallel Art


References and big helps,


 

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Discussion Starter · #11 ·

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Discussion Starter · #13 · (Edited)
I used a friends Mac scan tool today to check for DTC's. The only code was P0841 (LR pressure switch sensor circuit). I wasn't able to get a freeze frame of the parameters while driving, but I was able to check LR CL volume index value at idle in park which was 44.
Alldata gives me a flow chart to follow to check for faulty connections etc. but I don't have the equipment to preform some of the checks.
Alldata gives specifications info for Clutch Volume Index as follows:
" The L-R clutch volume is updated when doing a 2-1 or 3-1 coast down shift. The transmission temperature must be between 21-49 °C (70-120 °F). The clutch volume should be between 35 and 83".
So I reset this code and can borrow the scan tool again after a few drive cycles to see if it has set again.
At the bottom of Alldata's P0841 flow chart it list a TCM replacement. I was already anticipating changing the solenoid pack with a new Borg Warner part but I didn't find any P07xx codes. I can replace one or the other but I don't won't to replace both if one of them is still fully functional.
 
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