It will when your pulling or hauling something

Here is what mine does more specifically.
Empty flat road 1/4 throttle from stop in tow/haul mode.
0-20 1st gear
20-35 2nd gear
35-48 3rd gear locked TC
48 up 4th gear locked TC

You can feel the TC lock

In normal mode it shifts into 4th locked around 48-50

94 12 valve...thats the thing i am pulling something ... i`m pulling a 12` enclosed trailer approx. weight 2200 lbs. even when i put my foot in it a little it pulls great 1 & 2 gear, but when it hits third it almost immediately goes to OD. I did today turn the OD off & try it and it pulled hard the whole time...i guess its just a learning curve for me....i`ve always had gas trucks. Thank You for your help

If it is actually jumping from 2nd to 4th there is a problem. If it were me I would have the dealer check it out/fix it under warranty. From what I have seen there are quite a few TSBs on it.
FWIW - When I tow my 14' enclosed trailer with aprox. the same weight it pulls and shifts almost like it's empty. But, when I tow heavier weight(13K lb 5th wheel) it takes awhile to get from 3rd to overdrive. It gets to cruising speeds before shift.

what are TSBs?

Technical Service Bulletins

hook to a trailer, push tow/haul and then see how it shifts. the tranny will shift right into 4th lockup (overdrive) if it sees there is no load or the need to stay into 3rd gear lockup. if you hammer on it with tow/haul mode engaged and keep your foot to the floor, it will no do this. push the button 1 more time to get OD off, push the button 1 more time and it goes back to normal mode.

Is it possible that the trailer load is to "light" for it to feel the need to stay in 3rd to continue pulling. I have laid into it a little bit with the trailer attatched and it just seems to jump to OD. without the trailer and in "normal" mode it seems fine. I dont know this is a whole new world for me. Thanks

we will get ya on track SLVR. get with andy and we can get you the operation and description of that system. it will be clear as mud when we get done with ya! :tttt: lol

Thank You so much for your help.....i`m just a littled peared out that there may be something wrong with my truck & if there is i would like the dealer to take care of it while its on there dime. Thank You again ..take care