My sons 06 2500 has got to have something wrong.it seems to be fine with out a load. but hook a 10 K trailer to it and it cant seem to decide what gear it wants going up hill. it constantly shifts from 3-2 2-3. and in tow haul it sucks .it has a new trans from the dealer and they say its running normal, theres no way it can servive long doing this.also the trans is getting to 230*+ on a 6% grade. I have seen info on the GM GSV up grade and was wondering if this would fix this ? the trailer is a WW toy hauler and its just under 10K fully loaded. He has to put it in 2nd and watch old 1st gens fly by him any help?
Thanks R

 

There is an electronic part that needs replaced, along with a re-flash of the PCM. Mine does it from 1-2.

About the transmission temp issue, the transmission cooler has a thermostat in it, and overtime, it gets gunk build up and won't function normally. To get to it, you need to tie the condenser out of the way, then remove the intercooler completely. On the top right (facing the front of the truck) of the trans cooler, that's where the thermostat is located. To remove it, hold a torch on the cooler, and it'll pop out from the heat. Clean it really good, then reinstall.

 

OK what part?

 

I would bet the GSV is the cause, time for the PATC (GM) up grade, temp increase due to reduced fluid flow

 

I think the 48s are just plain junk,,I was finally forced to drive my 06 I was saving till a guy stole my old truck, and now my tuck has 8,000 miles and with a load it cant decide if it should shift at 2,000 rpm's or 2,500 rpm's, my old truck I knew exactly when it would shift and I could always back off on the throttle if it was pulling hard to make the Trans last, not this 48, its like when it feels it wants to shift it shifts.