TCC lock-up
 

I know the tranny isn't exactly computer controlled, but the computer does control TCC lockup and overdrive. Mine has been reflashed at the dealership to eliminate the TCC lock-up in third and doesn't lock up in OD until 52mph. This is good for normal driving as it doesn't down shift as much, but it does hurt the mpg's. Before if you were on the highway running about 60-65mph and had to accelerate, the tranny would kick down to third and then a couple of seconds later the TCC would lock up killing the acceleration. The flash got rid of that. But when towing, will not having the third gear lock-up lead to some over heating issues? It seems that Dodge goes from one extreme to another with their flashes. It either locks up too much (without the flash) or not enough (with the flash)! For low speed driving, (35-45mph) the truck really drinks the gas down due to not having the lock-up, but it pulls so much better without all of the downshifting.

i have the original flash, where TC locks up in 3rd at about 40mph, and then shifts to OD at about 45. i always leave OD off for around town driving. i was considering having it reflashed like you did, but i was wondering what effect that would have on higher rpm's, lower mpg's, etc at that in-between speed of 45-50 mph, which is where i spend most of my driving.

i don't think it will lead to overheating. older transmissions like my old chevy never had an OD nor a TC lock, and they worked fine. if you don't already have a cooler, you might want to add one just because its a dodge transmission.

how much has your mpg changed ?
overall, which way do you like best ?

I had mine done a year and a half ago probably for that flash. I actually don't mind it so much because when it shifts at (51 for me lol) it seems to have more kick and kind of launches the truck to 55 for me at least. The 45-50 range for me puts you a little under two grand if your climbing a hill, but once you lockup it drops to a hair below 1500. It really doesn't bother me so much, actually my transmission seems to have 5 gears now :) I talked to MonteC about it and he said it is perfectly normal. I think mpg did drop a bit so I get on average 13mpg hwy.

When I don't want overdrive I just push the OD button. Works every time.

My mpg's dropped about 2 mpg since I had it done. But the same time I had it done I put more aggressive all terrain tires on (had "P" tires on there before) so that may have added to the decrease of mpg also. I also put a timing chain tensioner on, and I always wonder of that may decrease mpg's also due to put more drag on the timing chain? I like the drivablilty of "after the flash", it appears to have a lot more pulling power (due to the TCC not being locked up.)

dhvaughan, that is a good point about the older trannys not even having the lock up. I guess I read about these tranny's failing so much I get a little worried! I do plan on added a cooler, I have already put a deep pan on that has cooling tubes at the bottom.

That decribes the way my truck is as well. I don't know about my highway mpg, but around town I average around 12mpg where I used to get 14mpg.

Transmissions that were designed for a lock up torque converter can overheat if they are run for long distances without lock up.

For most lock up transmissions cooler flow almost doubles when lock up is enabled, providing double the amount of cooling, as well as cooling down the torque converter. The torque converter is the transmissions main source of heat.