I have a 2003 3500 SRW 4x4, HO Cummins, 48RE transmission. I have a question about how the automatic works. It feels like it shift 1,2,3,4 pretty normal and then locks up at 48mph. Then coasting it unlocks at 45mph. Is this normal?
On my 95 I had if I hit the OD lockout button it would lock up in third at 30mph or so and I could cruise town with the camper on back and the tranny locked up. Now with this truck if I hit the OD lockout button it still doesn't lock up untill 48mph and then unlocks immediatly after letting off the accelerater. Is this normal?
I know it seems like stupid questions but I guess I'm just wanting to make sure everything is okay dokie before I head to myrtle beach pulling the camper the first week of June.

 

Sounds normal to me. Mine acts the same way

 

That's exactly how mine works.

Pete

 

I am happy that mine seems to be normal, but not happy that it works that way. I was hoping it would lock-up in second or earlier in third for in town and country road driving. Oh well, life goes on.

Happy Camping,
Scott

 

I had read somewhere here that the 4th shift was actually the TC lock up and the next shift was the OD engagement ???

 

TC lockup isn't a shift. If you put it in tow-haul, and are easy in on the gas, right at 30 is locks up in 3rd, then at 42 locks up in OD.

 

If the 03' 48RE is the same as the 04', the normal shift pattern is 1-2-3-3Lock-4Locked.

You can get the TC to lock in 2 if you place the shifter in "2" position with the tow-haul engaged. Leave it in "2" until the rev's get in the high 2K's and then shift to Drive. It will then shift to 3rd and lock almost immediately. If/When you're ready to shift to 4th (overdrive) just release the tow-haul & you should go to 4Lock.