Check this thread that is currently being cussed and discussed: http://www.jeepforum.com/forum/f67/new-pcm-now-tranny-thunk-3565642/

 

Hey mlane6223,

TSB 18-006-10 REV. C may relate to your vehicle:

SUBJECT:
Flash: MDS Drivability Improvements
OVERVIEW:
This bulletin involves selectively erasing and reprogramming the Powertrain Control
Module (PCM) with new software.
MODELS:
2007 - 2008 (DR) Ram Truck
2007 - 2008 (HB) Durango
2007 - 2008 (HG) Aspen
**2008 (LX) 300 / Magnum / Charger**
**2008 (LE) 300C/300 Touring (International Markets)**
2007 -2008 (WH) Grand Cherokee (International Markets)
2007 - 2008 (WK) Grand Cherokee
2007 - 2008 (XH) Commander (International Markets)
2007 - 2008 (XK) Commander
NOTE: This bulletin applies to models equipped with a 5.7L engine (Sales code
EZB).
NUMBER: 18-006-10 REV. C
GROUP: Vehicle Performance
DATE: October 08, 2010
SYMPTOM/CONDITION:
The customers may experience that the vehicle has a harsh engagement or has a
buck/jerking feeling at low speeds of around 12 mph (19 kmh) to 15 mph (24 kmh). The
customer may also experience a harsh engagement or buck/jerking feeling during highway
cruise control operation from 65 mph (105 kmh) to 75 mph (121 kmh). These conditions
are caused by excessive MDS transitions.
The MDS low speed engagement point has been changed to 21 mph (34 kmh). In addition
to the MDS low speed engagement change, enhancements from V8 to V4 and V4 to V8 in
all ambient temperatures and operating ranges have been made to make all the transition
less noticeable to the customer.

 

So, what does that TSB have to do with the transmission DOWNSHIFTS to 1st gear??? Hate to say it, but that TSB has NOTHING to do with his problem, since it is talking about harsh engagement/disengagement of the MDS, not downshifts. One other thing, we don't even know for sure what engine/transmission combination he has since he didn't specify, and it's not in his profile. My guess is it is the 545RFE though, since its shift schedules are much worse than those of the NAG1's.

 

OT warning!

So, what does that TSB have to do with the transmission DOWNSHIFTS to 1st gear??? Hate to say it, but that TSB has NOTHING to do with his problem...

I am glad FCA has a dedicated 'bot' assigned to our old, out-of-warranty (except the lifers) Jeeps!

The bot doesn't seem to me to be any more or less accurate than a lot of people posting here. A better sense of humor would be nice; the delivery always seems a bit dry and there are never any followups.

 

Do not know what transmission I have but do know 4.7 V8 engine - purchased this 3 weeks ago from a used car dealer in town and was just trying to see what I needed to do to fix the problem - but what is strange the passed (2) days I have not had any problems with the down shifting "BUT" its also been 20* in the morning and 45* in the afternoon. I live in upstate South Carolina and we normally have mild winters.

 

With the 4.7 engine you have the 545RFE transmission. It DOES NOT have MDS, so the TSB outlined above doesn't apply to you anyway.

As road tripper said, the transmission does "learn" the way you drive and somewhat adjusts to your driving style. This problem, however, is a characteristic of the the crappy stock shift schedules, particularly the down shift schedules. IMO, there are quite a few other problems with the shift schedules and torque management setting, but many of these are because the factory has it set up more for soccer mom's (slippery and smooth), although they haven't even done that very well. I believe that if you were to lower the "off throttle" 3-2 and 2-1 downshift speeds/RPM by a little bit (I currently have my 3-2 set to 14 mph and my 2-1 to 7 mph), it would resolve your problem. That's one of the many things I did to mine when I set it up to suit my preferences. I don't know if the stealer can do this and, if they could, they would probably charge an arm and a leg. IMO, the best way to go is to "spring for" a Superchips Tuner with the Advanced Transmission Tuning Application (ATT) and set everything up the way you want it.

All this being said, since this vehicle is new to you, I would recommend you go through everything and do all fluid/oil/filter(s) changes, unless you have all the maintenance records for the vehicle. One other thing, all of these electronically controlled transmissions are "torque sensitive" and, as such, if the vehicle is not tuned properly it'll affect the way the transmission operates. Verification and update of all of the maintenance items is the best way to address this, plus you'll then know exactly where you stand with regard to the vehicles upkeep. Good luck, and let us know how it goes.

 

if the recent owners (the various car dealers who owned your jeep before you) did any transmission work (such as replacing the fluid), it takes a bit of time for the transmission computer to 'learn' the new fluid characteristics and so on, and usually the clunk will go away in a few hours of stop-and-go driving.

there is a 'quick learn' procedure that can be done with a decent code scanner, but for me, it didn't affect the 'harsh downshift from 1-2 when coasting' after I replaced my solenoid pack... but after a few days it has fixed itself.

 

Mine has been doing the slight clunk since I have had it (7years). Never a problem

 

Mine does this too (2005 WK 4.7 545RFE trans) once in a while; from what I gather it is normal, even if it is annoying. It's been an issue since this powertrain came out in the WJ.

 

Hi I assume the fluid level is good , I just had same thing happen while I was away on holidays , did some research and I had a relearn done by trans shop. Cured my problem and he didn't charge me a dime . Might have to call around to see one quote was 185.00 to relearn others were less and couple no charge !
Good luck