QuestionQUESTION: I recently had my 2001 Chrysler Town&Country minivan checked after the check engine light came on and went off. I was told that the computer diagnostic check indicated a code P0740 (torque converter) which is a transmission concern. Since I have not had any problems shifting gears or any leaks, should I be concerned about this problem or is it something that should be dealt with immediately? Also, what causes this problem and is there anything I can do to prevent it in the future? Finally, if I need to have the torque converter repaired, what does it entail as far as approximate cost and time?
ANSWER: Hi Cori,
The code means that sometime in the past when the torque converter clutch should have effectively connected the input and output turbines together for the purpose of achieving better mileage and braking when slowing down it didn't achive the goal (to be within <60 rpm differential). If you can sense the slight reduction in rpm when you are going over 40-45 mph and rpm above 1750, that would indicate that the clutch is working electically. If not, then the wiring harness should be checked for possible damage. If there is slight slipping such as to set the code I would not be too concerned. This can be the result of operating at extremes of temperature at the time so that is another possibility.
In any case, there are many vehicles that don't have torque converter clutches and the "cost" is a modest reduction in fuel economy. So I would verify the clutch is felt, and leave it at that. Other than the wiring, repair would involve removing the transmission but I don't know the cost of repairing the clutch function as I have not had the problem myself. It could be this was a rare failure and will be of no concern. So careful watching is the best strategy in my opinion.
Roland
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---------- FOLLOW-UP ----------
QUESTION: Thanks for your response. If the transmission has a leaking solenoid pack, would this be something that needs to be dealt with immediately and if the solenoid pack is leaking, would this leak be noticeable without removing the transmission? In addition, could a leaking solenoid pack cause the check engine light to come on with the code P0740?
AnswerHi Cori,
I have to condition my answer by saying that I have not personally worked on this type of transmission. Based upon what I have read, if one of the several solenoids is leaking then it would be desireable to repair/replace as needed to optimize the function of the transmission and to possible prevent unnecessary wear to internal parts such as the clutches. As I view the solenoid pack it appears that the pack itself is removeable without removing the transmission, as it is found inside the large box on the side of the transmission that faces the front of the vehicle. The torque converter clutch is modulated by the L/R solenoid in its function so in that respect a problem with a leak in that solenoid could be the cause of an 0740.
The solenoid pack appears to be something that you can remove yourself and replace. I believe that a leak internal to the pack would not appear outside the transmission. You might try opening up the box and tightening the pack retaining screws (9 foot-pounds torque) in case there was simply a leak at the gasket interface to the valve body to which it is attached. I am not certain whether there is any benefit to trying to service individual solenoids as compared to replacing the pack in its entirety. You could investigate that question at the parts counter of a dealer and a trade-type parts store.
Roland
PS Thank you for the very kind previous rating.
