I use it to tow a trailer and farm equipment and 3rd gear usually is the best however I believe it is the torque converter lock that kicks in and then it's lugging too much and it keeps kicking in and out and when it is in it seems the rpms fluctuate like it's not holding good. I am wondering if there is an electrical way to deactivate it? Like Dodge has a button but that may be for overdrive which would be the same as putting this in 3rd. When it's towing in 3rd it's just right without the t.c. lock and in 2nd it's too high rpm and not enough mph.

Sorry no way to electrically defeat the torque converter clutch that will not set a code and turn on the SES light.

 

Just put it in third gear. You don't need overdrive when towing. If you can keep the TC locked up in 3rd when towing it will drastically lower the transmission temp. Otherwise you should definitely be getting an auxiliary transmission cooler.

 

There was an option on some of the 2nd gens for a towing mode for the transmission but I don't know how it was configured.

I go with what Les advised and just keep it in 3rd per the owners manual.