Chrysler Repair: code 700, 740., torque converter clutch, dipstick tube

Question
HI Roland.  I have a 2001 Town and Country minivan. Yesterday my idiot light that looks like an engine came on and stayed on.  I assume that's the check engine light.  Took it to VIP today to have the codes read.  It came back with a code 740 which I was told is the Transmission Control System Malfunction and also a 700 code which I was told was a temperature control sensor.  He cleared the codes and as of yet they have not come back on..but i have only driven home from there which is about 6 miles at most.
Couple of things I have noticed happening about the same time this check engine light came on..the van is running a little, not a lot, but a little hotter then it was and my heater fan inside the vehicle is now always on low even when the fan is shut off.  I was wondering if you had any ideas about what I learned and if possibly either or both of these things might be under warranty? My van seems to be running the same as it always did, haven't noticed any performance issues.  Thanks for you help, I really appreciate it.
Estelle

Answer
Hi Estelle,
The 700 code only is there to say that another transmission code has been recorded (nothing to do with a temperature sensor).
The 740 says that the torque converter clutch lock-up device didn't actuate at some point. You probably notice that when you reach cruising speed there is a slight decrease in the rpm of the engine, almost like a mini-gear shift, and that is because the torque converter input and output turbines have been tied together as an economy move (no slippage). It is not of itself a big problem.
It could be that the trans fluid is a little bit low, so check the trans dipstick once you have driven for awhile. If you have to add fluid only use ATF +4 type fluid, never use Dexron. Add it a little at a time thruough the dipstick tube, and don't overfill.
Other than that, if it keeps coming on it may be due to a low pressure problem in the transmission itself. A trans shop would need to access if that were the case or not. If so, it could either be the internal pump of the hydraulic fluid switching box (called the solenoid pack) that is at fault.
I suspect that the van is no longer covered by warranty. But this is not going to cause a driveability issue in and of itself. It may cause a 5% decrease in gas mileage.
That is how I see it.
Roland