Chrysler Repair: MIL code P0740, torque converter clutch, torque converter clutch circuit malfunction

Question
Hi,

I have a '02 T & C with 78K miles.  I have a P0740 code "torque converter clutch circuit malfunction"

The van runs fine.  Just had the fluid flushed and tried to clear code but it came back

Thanks for any help

Answer
Hi Eric,
This code says that the lock-up of the two vanes of the torque converter is not occurring when the speed of the van goes over 45 or so mph. It may be that this is the case or it may be that the type of trans you have doesn't have the lock up feature. The lock up feature is a gas-saving option that totally attaches the vanes so there is no slippage once you are cruising, instead of maybe a 5-10% slippage. Many cars have trans's that don't do this so it isn't a major issue. But if you notice that there is something new in the way the rpm changes when you step on the gas when cruising (e.g. the engine rev will rise without a concomitant increase in the speed) then the lock up may be present and it isn't working. If it is missing there are two possibilities: the electrical connection to the lockup maybe open or the lockup may not be working itself. The former is an easy fix, the latter is not because it requires removing the trans and opening it up (very costly, you will never save that much gas in the future life of the van). Because I don't have any manuals about the trans's used in the van's after '98 you may have to ask a dealer whether this is a real problem of just a "phantom" code because your trans doesn't have the lock-up feature. I wouldn't get into trying to repair this if everything else with the trans is fine. You may just open another "can of worms." If you are under warranty then and don't have to pay for it then checking the electrical would be good. But I would be hesitant to letting them remove and open the trans to fix the lockup itself, even if Chrysler pays for it.
Roland