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Discussion Starter · #1 · (Edited)
I have a 2011 Chrysler Town and Country Touring L (62TE transmission). I purchased this vehicle almost two years ago from a dealer with 115k miles. When I test drove it, everything was fine, but about halfway on the 100 mile drive home the Check Engine Light (CEL) came on (now I know I should scan the car myself before driving off the lot, but you live and learn). The code was a P0740 (Torque Converter Clutch Solenoid Circuit/Open Circuit Malfunction). I never thought much of it because the van drove and shifted fine and the mpg were in range.

About six months ago I decided to try to tackle the issue. One of the first suggestions was changing the transmission fluid since old tranny fluid can cause the code. I dropped the pan and changed out the oil in the pan (did not do a complete flush), as well as the filter. There wasn't anything alarming in the pan (i.e. no "coffee ground" metal shavings), just extremely fine metal shavings attached to the magnet (to be expected).

The code soon came back. I chose to ignore it again because the van was still running great, but I live in California and my registration was up late October, which required a SMOG check. I didn't realize it at the time, but ANY CEL will be an automatic fail. And since my P0740 has been on so long, it is also stored as a permanent DTC (PTDC), which means I can clear the codes, but then I have to drive at least 15 warm up cycles and 200 miles in order for the PDTC to be ignored for SMOG (without the code coming back). So, long story short, I have to fix the P0740, workaround the SMOG test, or spend like $700+ trying to fix it in order for them to give me an "I'm sorry you spent so much money because of us" pass.

This weekend I replaced the TCC solenoid because that is a common culprit. However, about 5 miles on the freeway the code came back as "pending". I read on another forum that if you drive less than 35 mph for 30+ miles you can trick the computer to clear the code because the code condition was never met. So, I decided to try that... I cleared the codes and drove on side streets to Home Depot 25 mins away. About 10 miles in the code came back pending. Then on the way back, the code tripped the CEL (so the computer had experienced the fault condition twice over those drive cycles).

So, now what do I do? Does anyone have any additional ideas so I can at least beat SMOG (i.e. do enough so I can drive 200 miles without tripping the P0740 code). I can take it to a shop and get it diagnosed for probably $150 and I am assuming they will recommend replacing the Torque Converter. But, I was hoping someone on here might have another idea before throwing in the towel.

Thanks!
 

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Have you checked the grounds and the harness around the transmission? Sounds like an intermittent issue so possible wiring issue and not a "hard" fault with the transmission itself. Pull the connector and check for corrosion.
 

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When you changed the fluid, did you also do the filter? A flow restriction could cause erratic TCC behavior. Aside from that it's wiring or the converter itself.
 

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Discussion Starter · #4 ·
When you changed the fluid, did you also do the filter? A flow restriction could cause erratic TCC behavior. Aside from that it's wiring or the converter itself.
Hi! Yes, I did swap out the filter. Sorry for neglecting to put that in the original post. I have edited it to include that point.
 

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Discussion Starter · #5 ·
Have you checked the grounds and the harness around the transmission? Sounds like an intermittent issue so possible wiring issue and not a "hard" fault with the transmission itself. Pull the connector and check for corrosion.
I glanced at the connector and wiring when I swapped out the solenoid, but I did not do a thorough check. All the wiring immediately near the connector is surrounded by a thick plastic wire conduit, so I figured it was pretty well protected. Is there any specific method/process for checking wiring so I don't miss something?
 

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Discussion Starter · #6 ·
So, this is what I'm working with in terms of the electrical connectors. I don't really know what I am looking at. Does anything look abnormal?

  • Is the different colored pins corrosion? Or is it just made out of a different material?
  • It appears there is some sort of fluid or perhaps solder or something around the base of the pins. Does this look normal? Or could there be a short there?
  • Either way, it looks like there is some transmission fluid in the connector. So, I will try to clean both sides out with some alcohol spray and see if it looks considerably different afterwords.
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Clean that connector up and hopefully that's all it is. If not, here's the troubleshooting for that code and the install of the solenoid it says might be causing it.
 

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I had the same issue and it ended up being a torque converter. The trouble code explanation is somewhat misleading as it suggests an electrical/solenoid issue. The code actually sets when the PCM detects an unexpected difference in engine RPM (crank shaft sensor output) to trans input speed sensor. During normal operation the torque converter locks the engine up with the transmission at a 1:1 ratio when the tcc is applied. When the PCM applies the TCC circuit it expects to see similar speeds between the engine RPM and transmission speed sensor. This code will set when there is a large difference under these conditions ( i think it is 200 rpm difference).

I would suggest taking this on a test drive and cruise at about 35 mph. While cruising slightly apply the gas pedal and watch engine RPM. If engine RPM jumps or "revs" you know the torque converter is slipping. This test is very sensitive and takes a very tuned in feel of how your vehicle operates.

That is my experience with the issue and when I swapped my torque converter the code went away. Also, about 2 months after swapping the converter my transmission had a large internal failure (metal shavings, slipping, ect) that I think may have been related to the torque converter.
 

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The connector appears pristine. That is just silicone "di-electric grease" in the connector, which is wise to use to keep out moisture. I would pack much more in. Some of the copper terminals are half-tinned. Don't know why, but appears factory and no corrosion. If the torque converter lockup doesn't work, you will just lose the better mileage benefit, which might be a 1 mpg loss. No transmissions had a lock-up converter until around the late 1970's as I recall.

I agree the code is misleading. If truly an electrical problem with the solenoid, you should be able to fix that either in the external wiring or with transmission in car from below w/ the pan off, though might need to remove the valve body. Before all that, measure the resistance between the 2 solenoid pins on the transmission side, referring to a schematic. If it doesn't read infinity (open), then the solenoid itself is likely fine. I would expect something like 20 to 100 ohm if good. Reconnect and repeat at the other side of the cable (transmission control module or PCM?).
 
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