Vehicle: 2002 Dodge Grand Caravan, 3.8L motor, 4-spd transmission, about 165K miles. First some brief history. A couple of months ago the transmission went into limp mode while my wife was driving it home. It threw OBDII code 700 (transmission control system malfunction) and code 750 (Shift solenoid A malfunction). I did some research but due to uncertainty I decided to have a local transmission shop do a driving diagnosis. They concurred with the faulty solenoid pack so I had them install a new one along with a fluid/filter change. Problem solved for about a month. Then last week (again while my wife was driving!) the van began to shudder (slip?) while driving at highway speeds. After additional extensive research I came to the conclusion that the wrong fluid was likely the cause. A call to the shop confirmed my suspicions as they admitted to using a generic all purpose fluid and not specific ATF+4. Half a Saturday and about $120 later, I installed a new filter, several heli-coil inserts where the shop had stripped out pan bolts, and I did a system flush with 11 quarts through the transmission cooler lines (system holds 9.x quarts). However, the problem does not seem entirely fixed. After a good 10-15 minute warm up, while driving at 40+ MPH, tach readings between 1200-1800rpm the vehicle will start to shudder (slip) with visible tach fluctuations as the engine appears to attempt to compensate for the problem in the transmission. I think the condition primarily occurs during the torque converter lockup stages of operation (4th gear?). The problem appears most prevalent while on level or uphill sections of road – under more load I suspect. I pulled the battery cable for a few hours to attempt a computer reset, but am uncertain if the computer will go into learn/retraining mode doing this on 2002 vehicles. After driving the vehicle roughly 50+ miles today (some city, some highway) things seemed to improve, but only during the last 20 or so highway miles. I have had my scanner connected all day and no codes have been thrown. My questions: Can incorrect fluid cause a slip or shudder condition? Can I reset the computer, or does it require a special tool/scanner? How long does it take to “retrain” itself after a reset? What are the chances the input or output speed sensors are fouled or faulty? Thank you in advance for any advice from forum readers/contributors.

 

Welcome to DF

Yes the wrong fluid in the 41TE/A604 can cause a shudder. But if you are feeling the shudder after 4th gear and the torque converter has gone into lock-up. And no codes, I would say the problem is with torque converter. Not because of wrong fluid, but because the torque converter is coming apart. If the sensor were bad, the transmission would be in limp-in/failsafe. Now if you put the wrong fluid in a 3 speed transmission, it will shift fine with no shudding problems.

 

Master Tech:
Thanks for the thoughts. Pan was pretty clean when I pulled it off to exchange fluid. Would I expect metal shavings of some sort in the pan if the torque converter is going South?

 

Some follow up and additional Q’s after several more days of driving the van, some checks and fixes, and additional research on this and other sites. Checked and gapped all plugs and checked plug wires. Do not have specs for coil pack expected impedance for each of the six outputs, anyone have these numbers? Pulled throttle body and thoroughly cleaned. Checked IAC, MAP, PCV valve and TPS while I was at it. Tried to run down an external EGR valve but apparently it does not exist on early model year 02’ vans. Cover plates are present where the system should bolt on, but it is not there. Replaced fuel filter – engineers should be shot for the catastrophe of a location. The surge/slip/shudder condition still infrequently occurs and a notable bump up/down appears prevalent during torque converter lock/unlock. Also, another condition now manifests while going downhill - motor (tach) has a notable 600+RMP drop and then almost instant recovery. Happens both in and out of cruise. My uncertainty still revolves around rather this is a computer/motor issue or the torque converter ready to shell itself. When the RPM’s start to surge it almost appears that there are conflicting sensor inputs being sent to the PCM and it develops a sine wave cycle attempting to react to the conflicting inputs. This is why I continue to have reservations about rather it is the transmission or all the computer hooey that runs the vehicle. I have read several similar posts with the primary two outcomes as either torque converter or computer issues/upgrade/replacement. Now the follow on Q’s. How long (and how many fluid changes) should it take for the computer to re-learn itself with the correct ATF+4 fluid? With no DTC’s showing up can a shop emphatically diagnose a bad torque converter? Anything else I am missing and should check? Thanks again for any thoughts/advice.

 

When the transmission goes into lock-up, after a short drive. Does the van feel like its shaking badly? Steering wheel shake. The only time you will see metal in the pan, is when planetarys, reaction plates and snap rings break.

 

No notable steering wheel shake or overall vehicle shaking per say. A slight "bump" in some cases and notable vehicle/tach surging in the more severe instances, with notable cyclic vehicle speed increase and decrease as the problem cycles. Accelerating or decelerating usually causes the problem to go away.

 

Any way to check the torque converter without special tools, or does it require special diagnostics equipment?
Thanks.

 

You need a DRB3 To check the transmission, I did a search and found this TSB. Is this what you are feeling?
SUBJECT:
Surge With Transmission at Full Lock-up
OVERVIEW:
This bulletin involves replacing the Powertrain Control Module (PCM) and flashing the
TCM with updated software.
MODELS:
2001 - 2002 (RS) Town & Country/Caravan/Voyager
NOTE: This bulletin applies to RS vehicles equipped with a 3.3L or 3.8L engine
(sales code EGA, EGH or EGM) and a EGR valve. EGR valves were installed
on all 2001 models and some 2002 models.
SYMPTOM/CONDITION:
The vehicle operator may experience a surge. This conditions is more noticeable at 40 - 50
mph with the transmission in full lock-up on a slight incline under heavy load.
DIAGNOSIS:
Using a Scan Tool (DRBIII®) with the appropriate Diagnostic Procedures, verify all engine
systems are functioning as designed. If DTCs are present record them on the repair order
and repair as necessary before proceeding further with this bulletin.
If the customer describes the Symptom/Condition perform the Repair Procedure.
CAUTION: These service only PCM's and TCM flash should only be installed to fix
this exact condition. This PCM and TCM flash should not be installed for
any other purpose.

 

Yes, this is exactly what I am feeling...except I have no EGR valve. I have seen this TSB in the threads and would be happy to get a new PCM and TCM flash if I had confidence it would fix the problem. Would the EGR valve necessarily have to be part of the equation? Probably need to go ahead and have the torque converter checked.
Thanks again for the info and advice.

 

Do you know what the TSB number is for the above listed PCM flash?
Thanks.