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Discussion Starter #1
I have a 2000 Dodge Grand Caravan with 85,000 miles that is displaying P0O700 and P0740 codes. I know that P0700 is an information code that means there’s a fault code stored in the transmission control module; this code is P0740, which refers to the torque converter clutch, specifically, no RPM decrease at lockup. My understanding is that when there are problems with the torque converter lockup clutch, there will be a shuddering felt from the clutch trying to engage. However, there is absolutely no shuddering with this transmission, but there’s also absolutely no indication of lockup, either; this van runs perfectly and shifts like glass, just no lockup. Since everything else feels great, I’m thinking the problem is with the transmission control solenoid; does this make sense? What are good brands of replacement transmission control solenoids?

Thank you.
 

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Welcome to Allpar. You may only get a shudder if it is trying to lock-up or is partially engaging. It sounds like yours has no engagement at all.
Usually this is not an electrical solenoid failure, but more along the lines of internal hydraulic leaking or mechanical wear.
Do some diagnosis before replacing anything. Any fluid (ATF+4 only) and filter change history?
 

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Discussion Starter #3
Thank you. I have to admit that I last changed the fluid and filter at about 30,000 miles. I did use ATF+4, though. What other diagnostics should be performed?
 

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You will want to go through each of the POSSIBLE CAUSES and see where one fits. This transaxle was used in a wide variety of vehicles and pretty much any factory service manual or Transaxle Diagnostic Procedures book that covers a 41TE will give you more details of common diagnostic methods. A large public library may have Chrysler service manuals for loan. Amazon or ebay also have them for sale.

P0740-TORQUE CONVERTER CLUTCH CONTROL CIRCUIT
When Monitored: During Partial Electronically Modulated Converter Clutch (PEMCC)
operation.
Set Condition: The trans must be in PEMCC, input speed greater than 1750 rpm. The
TCC/L-R solenoid must achieve max duty cycle and NOT be able to pull the engine speed
within 60 rpm of input speed. The code sets after 3 attempts at less than 30 deg of throttle
angle.

POSSIBLE CAUSES

CHECKING SYMPTOMS AND POSSIBLE CAUSES:
LOW BATTERY VOLTAGE CAUSING SYMPTOM
CODE P1784 ALSO PRESENT
NO PEMCC TO FEMCC TRANSITION DURING TIP IN
OIL PUMP BUSHING LOW PRESSURE
SOLENOID PACK ASSEMBLY L-R SOLENOID OPEN
VALVE BODY VALVE MECHANISM
INTERMITTENT CODE P0740
 

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Discussion Starter #5
Thank you, ImperialCrown, you clearly know your stuff. I will check with our local library to see if they have one of the books you mentioned. I won't be able to work on the van until the weekend, though. Can the solenoid pack be bench tested?
 

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If there is an O'Reilly autoparts near you our stores (at least mine does) have a hi end scanner that can dig deeper to find what set off the P0700
 

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The sol pack can be tested on the car. Knowing the pinout and wire colors of the 8-way connector will allow you to check the TCC/LR solenoid continuity of a few ohms as stated in the P0740 Possible Causes list.
There may be more codes stored in the TCM (transaxle) half of the controller as well as the PCM (engine) half, which you have already got P0700 and P0740 from. The P0700 may be because of the P0740 fault code.
 

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Discussion Starter #8
Thank you. I was able to score a set of factory manuals off of eBay, including a transmission manual, so when I receive these I can try the diagnostics you're suggesting. I asked about bench-testing the solenoid pack because I figured you could better see the action of the solenoids.

Here's the $64,000.00 question I never asked; how reliable is this van? My son uses it to drive to college, about 10 miles each way.

Thanks again.
 

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for the most part as long as you keep up on maintenance they're good. My 2000 GC has 180,000 miles with the only major repair being a new Catalytic converter and a burnt out ECM (which I think was my fault since I crossed two fuel injector wire by mistake) I did also have my power steering pump go out as well about a year ago. This is with the 700 miles one way trip that I make from college to home about 4-5 times a year
 

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Discussion Starter #10
Thank you. My question is specifically regarding the current absence of lock-up. I realize this may be difficult to answer, but is this the kind of problem that can get you stuck somewhere? My wife and I are still debating how much we should potentially spend on a 13 year-old vehicle.

Thanks again.
 

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That's a hard thing to say. The van could run well for a long time without the lockup working and all you'd see is a slight drop in fuel economy.
However, the torque converter could be self destructing which would mean bigger problems as it would eventually cause debris in the fluid which will affect other areas of the transmission.
 

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At 14 years old but still fairly low mileage, how is the condition of the rest of the vehicle? If there are other things it needs, is a torque converter/front pump/cooler replacement in the cards?
The shop may want to install a reman which is quick and easy or overhaul it in order to cover themselves. A used transaxle is a gamble.
Having the pan down for a filter and ATF+4 change may offer some clues as to the amount of internal wear by seeing what's in the bottom of the pan. Does this van look to have some years left in it? Is it worth sinking a transaxle rebuild into?
Do some preliminary diagnosis first, get some opinions and estimates next and then you can decide the $64,000 question.
 

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Discussion Starter #13
Thank you. Everything on this van works, and the ride is very smooth and quiet. The only cosmetic issue is a cracked front bumper cover. There are also a few stains on the carpet which may come out with a good cleaning. I've changed the oil every 3 - 4,000 miles. The tires, Michelin HydroEdge (great tires!), are in great shape and should be good for at least another 50,000 miles. The windshield and the radiator were both replaced and the A/C recharged within the past year. A complicating factor is that we also have a 2008 Chrysler Town & Country Touring, which is very nice but I'm not happy with replacing brakes every 20,000 miles and adding oil every 1,000 miles. My preference might be to sell the Chrysler and fix the Dodge, but my wife, a.k.a. She Who Must Be Obeyed, isn't crazy about driving a vehicle this old.
 

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Okay, I dropped the pan yesterday, and it was actually pretty clean. The fluid was red, and it didn't have a burnt smell, although I can't say it smelled "fresh". The magnet in the pan had some filings on it; I'd guess maybe 1/2 of a teaspoon. I also removed both speed sensors and cleaned them off. The input sensor was clean, while the output sensor had some filings. It took about 5.5 quarts of ATF+4 to refill. I disconnected the battery for a few minutes to clear the code, but there was still no lockup. Perhaps I'll try cleaning out the solenoid pack, or maybe (unless there are other suggestions) I'll just wait for the manual before I try anything else. Are the lockup components part of the torque converter, or are they separate components?

Thank you.
 
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