Hello, my second post.
I have an 04.5 48RE bone stock auto and it seems to work flawlessly but there is one shift that I fine annoying. Loaded or empty, when it goes into
4th, it will not lock up until the speed gets to 49mph. When the speed limit is 45 and I try to hold it at about 45, it will never lock up. If I speed up to 49will lock up and then I can slow back down to 45 and it holds it there. I feel it is not good for the TC to be driving for miles and miles on a street that has a posted 45 mph with the TC slipping so I will speed up till it locks and then slow back down. Is there a mod I can do? Does chips allow that kind of mod? What about an E Brake like PacBrake? Does it have the ability to control lock up?
Thanks for all replies.
Tony
PS: How do I add my truck to my signature?

 

I believe the reason it won't lock up at 45 is because at that speed your too close to lugging the engine with 3.73's. On mine, with 4.10's, it lock's up at 45, but will stay locked all the way down to 39.

You can install a TC lock up switch and this will also allow you to lock the converter in any gear I believe. Search the forums, there is a write up on here about how to do it. Just remember to unlock it before it shift's gears as a locked shift is violent and extremely hard on stock parts.

 

I installed an ATS copilot which allows me to select my lockup speed. Some guys don't like them but I am pretty happy with mine. I normally keep it so it locks in the 50 to 52 MPH range and reduce the lock range only if I need compression assist braking when heading down hills with my camper or towing the boat.

Tony

 

Tow/haul changes the lockup speed to about 45 in 4th if your easy on the throttle. Something I recently learned is if you set the cruise with TC locked in 4th then reduce the speed using the cruise controls it will stay locked to a much lower speed in 4th than it will without the cruise activated. I've been down lower than 35 locked in 4th that way.

 

My truck, it will lock up at exactly 50mph, everytime. But...... If I am going up a long hill where there is a load being put on the trans,and I only get to about 40, and it's still in 3rd, it will lock up also.That is with tow/haul off, running with overdrive on. If I put it in tow/haul mode, it locks up at exactly 30mph in 3rd. Once it's locked in tow/haul, I can drop that speed down to a little over 20mph, and it will stay locked in 3rd.

 

Thanks for the replies. Mine is the 04.5 and in tow/haul, OD (4) is locked out. The main reason I do not like T/H. Engine revs higher than I like even when on flats and will just not shift up when T/H is activated. When driving empty on long flat 45 mph roads, the engine sounds like it is locked in 3rd. Seems like the slipping would not be good and would gen. heat. I understand if I'm towing heavy but this happens even when not. I also wish it would shift to 4th while in T/H like the later models do.

 

Sounds like your stalk switch is programed for o/d off instead of T/H. If you go to the dealer you can get it reprogrammed.

I wouldn't worry about over heating the transmission while cruising unloaded with the T/C unlocked. The load on the transmission while unloaded isn't much and even while loaded you would need a good load to over heat it. The T/C in my 92' is a non-locking type and it never has a problem, even with the 3.54 ratio it has. Granted it's only half the hp and 200 ft. lbs less of torque, but it's the same basic idea.

You could always stick an aftermarket t/c and valve body in the truck and that would really put the power to the ground when unlocked.

 

Quote: Sounds like your stalk switch is programed for o/d off instead of T/H. If you go to the dealer you can get it reprogrammed.

Thanks. So I just tell the dealer that I want the "stalk switch" reprogramed to allow 4th in TH?

 

I believe he meant stock switch....

 

Yeah, just go in there and talk to someone at service about having the overdrive off button reprogrammed to be the tow/haul program instead. Once that's done, when you activate the button, the T/C will lock at around 30 in 3rd, and then at around 45 it will unlock, shift into 4th, then lock back up. You should find that nice to use when accelerating to speed's above 45, it will pull real good with a lesser amount of fuel used.

 

No I meant stalk, as in "shifter stalk".

 

You must understand how the factory set these up, rather confusing. 04 and earlier you had overdrive lockout. 04.5 the shifter was remarked to tow\haul, however, the function is the same as earlier, just a overdrive lockout,no tow\haul. In 05 the dash markings are the same as 04.5,( tow\haul or normal ). BUT the 05 has NO overdrive lockout, it has what we know now as a tow\haul mode. Which has advantages over normal for towing etc. The 06 has three settings ( tow\haul AND overdrive lockout and normal ). The 06 has the best setup of all , However it lacks in the fact you cant maintain tow\haul with overdrive locked out at the same time.
I dont think I'd reprogram to lockup sooner than 50 in 4th.At speeds 40-50 under no load it wont hurt a thing to run in 4th NO lockup. With a load at those speeds I'd I'd lockout overdrive at which point it would shift to 3rd and lockup which would be much better pulling a load. ( Better oil pressure to motor , better line pressure to trans, with lockup less heat in trans ).
You see the bottom line is they want you to buy new. The new 07.5 6 speed auto. is by far the most desirable. Here you got tow\haul and normal AND a rocker switch that allows you to lock in any gear you want

 

OK so can the dealer reprogram the T/H so it will not lockout OD in my 04.5? New truck is out of the question. Would love to have one but the economy has tanked and apparently most everyone is taking a wait and see and very few are buying new or used. If I had the cash.....................
Thanks,
Tony

 

Yep, they can reprogram it to the T/H that locks up in 3rd then shifts into 4th. Though you lose the ability to lock out overdrive with this, you can still always downshift to 2nd and still be able to run up til' around 40 - 45, maybe higher with 3.73's, before you redline.

 

I think I got it. So if I have it reprogrammed to allow lockup in T/H & I'm between approx. 40 to 50 mph, it will be locked up in 3rd. To go a little faster and depending on load and terrain, it will most likely go to 4th and then lockup. Coming back down, if not in T/H and descending a hill, I push the T/H button, will it down shift to allow an exhaust break to function or does the EB have a program for that. Now with OD lockout, it will downshift to 3rd and then lockup if decellerating. I don't have an EB but am considering one even tho my 48RE has the wrong thrust washer.
Sorry for all the questions but I want to get it right the first time and not regret having it reprogrammed.
Tony