NuttyMopar:

I run in tow/haul all teh time. At light throttle in town it locks 3rd at 35 and moves to 4th locked at 45. Way better that normal mode like you stated where it stays in 3rd no lock at 45. Slightly better fuel efficiency (1 MPG) in town using tow/haul. (This is for 05 versions not earlier autos).

 

ok hang on, so u guys are saying the TC doesn't lock in 2nd? cause mine does or at least i think it is. the shift sequence if i take off slowly is 1,2,2nd lock,3... if i take off alittle faster it goes 1,2,3,ect. Is this "mini shift" i'm feeling in second the TC locking or is my tranny slipping? this is a compliant ive had since day one. sometimes in traffic given the right speed and throttle, it seems like the TC locks, unlocks, locks, unlocks, in 2nd. like i'm confusing it or something. i hate it, my truck seems to be the only one here that does this, is this a problem?

 

It probably is jumping between 2nd and 3rd gear...

My Dad's '05 will do that occasionally.

Merrick

 

My 04 doesen't go into 4th with the tow/haul on?? It goes to 3rd, 3rd lockup and thats it.

 

dencordle,

The tow/haul mode is different when you talk about 04/04.5's, 05's and 06's.

My 04.5 in Tow Haul mode would not run overdrive, like you are saying. 3 lockup was the last event.

In my 06, the TC locks in 3rd (2nd when loaded) then shifts to 4th locked when in Tow/Haul. The coolest feature of this is in deceleration. The TC stays locked down into 2nd and helps to slow things down. There is also a O/D off switch that locks out 4th completely.

Yours is normal for the model year truck you have. The guys talking about lockup in tow/haul in 2nd/3rd/4th gear have 05's and 06's.

 

Who Is making a add on that will change the 04.5 converter and shift points so we to can have a real tow haul not a on off overdrive

 

I seriously doubt that happens on ANY stock transmission. I know it does not happen on the 05's and not on the 06 I drove. The lockup is almost immediate after the shift and unless you are under a bit of load and low throttle it is hard to catch but there is definitely a shift event then a lockup event when going into OD in either normal mode or tow/haul.

The shift sequence on my 05 is:

Normal: 1-2-3-lockTC-4-lockTC

Tow/Haul: 1-2-lockTC-3-Locktc-4-lockTC

Manual shifting is the same as Tow/Haul.


TC lock in 2nd and drive is generally about halfway thru the acceleration range so it is a noticeable difference. Lockup in OD is a almost immediate in tow/haul but in normal mode and under a load it is definitely later.

When down shifting in Tow/Haul mine does lock the TC on deceleration. It also does the same thing if I manually shift into 2nd whether in normal or TH.

 

In tow/haul mode: If it unlocks during/before/after the shift from 3rd to 4th, it is only for 1/2 a second, because I can't tell. It feels like a locked shift from 3rd-4th.

I have only used the tow/haul a few times since I bought the truck 3 weeks ago, but that's what it "feels" like.

 

Merrick Cummings

Merrick is right! Normal lock up on a 03 and 04 is at 48mph. If you have OD locked out then the TC will lock and stay locked in 3rd and if you unlock the OD lock out while it is locked it will stay as long as you are above 48mph and have the accelerator depressed. If you are putting along at 45 mph in 4th you will not lock the TC until you get over 48. Only 04.5, 05 and 06 have a real Tow Haul. 03 and 04 have an OD lock out only. 05 have no OD lock out (04.5 also) The shift between 2 and 3 is unlocked if it was locked in 2nd. Only the 06 will stay locked decelerating to 2nd. If you want to control the TCC you can add a TCC from BD, ATS, or Banks or look up a post from John Rodriguez on the subject of something like "definitive how to lock up torque converter" If your not happy with the shifting try the advice of
nutty mopar
If you want better or firmer shifts ya gotta upgrade the TC and Valve Body. ks

 

Late 05's will also do this. Mine is a 05-05 build and will lock the TC on deceleration both in tow/haul and by manually shifting into second.

I have not been able to verify the TC lock in 2nd while in normal mode because the shift happens so fast. Since tow/haul tends to hold the shifts longer I have been able to hear the 2nd lock in tow/haul with some creative driving. However, I suspect it is locking in 2nd normal mode because of the funky 1-2 2-1 shift while under light throttle. I suspect what is happening is the ECU is commanding lockup right after the 1-2 shift and there is not enough speed and apps position to support the rpm drop generated and it immediately drops back into 1st.

As djbikeman says it "feels" like the shift is locked on the 3-4 shift and I can't dispute that because it does. The only way I have been able to verify the shifts and TC lock is the lack of a muffler and a better tone from the exhaust to hear the rpm drops when the shifts and locks happen.

I also supsect that even in the 05 model year there are some differences in the programs loaded into the ECU that are effecting the shift and lock timing.

 

I went on a mission yesterday to find out if the 3-4 shift occurs locked or not.

What I have concluded is, that, in some scenario's, I THINK it does. I THINK it does shift locked 3-4 when your foot is on the accelerator, but the truck is loosing speed, or if your foot is completely off of the accelerator.

I have also come to the conclusion that, the 3-4 shift does not occur locked between 1/4 and 3/4 throttle. (I did not try WOT shifts). The 3-4 shift contains a extremely quick flash of the converter during the shift. If you are not careful you will miss the 50-150RPM drop right after the gear change when the converter locks up.

I was not towing yesterday, so I do not know if the TCC locks in 2nd gear with just tow/haul, but the TCC definatly locks in Manual 2nd with Tow/Haul. I did not try manual 2nd w/o Tow/Haul.

One thing the truck defiantly needs if you uprate the power is a new Torque Converter. The factory TC fluid coupling is just about perfect for a stock truck, but I feel that even as little as 75HP can begin to pull through the factory TC's fluid coupling, creating more heat, than "go".


Merrick