Hi........ I'm new to this forum and would be interested in hearing opinions on the pros/cons of towing with cruise control. I've got an '04 2500HD Silverado with the D/A and tow a 7,500 pound fifth wheel. From what I can tell, my cruise control can tow way better than my right foot when it comes to pulling at highway speeds in the hills! Way fewer downshifts and the speeds hardly ever vary more than 1-2 mph. Any potential harm from letting the cruise do the drivin? Thanks!

Smurph
:rolleyes:

I've only had the oppurtunity to use it a couple (100+):h ) times while towing. Have no problems with it. Just find a SAFE speed you can set it on and hope for open roads that don't have you disengageing it.:)

I use the CC as much as possible, especially towing.

Me three.

Me Fou... wait a minute, my truck didn't come with cruise control:(

Dan

You will probably get better milage without the CC but I would Use it if milage is not a concern.

I use CC all the time while towing... it is your very best chance at getting top MPG our of your rig! :ro)

VR

As long as the truck isn't downshifting frequently let the CC do its job. The only downside I have found is when climbing hills or grades it is easier to ease into the throttle on the downside and gain a little momentum going into the climb. ;)

IMHO the GCW has a lot to do with whether using CC gives better mpg's or not. JJ :)

Ditto JJ's comment. I find the only drawback to using the cruise control is that it doesn't react fast enough at the beginning of the grade. You are well into the hill before it reacts and you find yourself behind the curve the rest of the way up.

we just finished a long tow with a 9000# fifth through WI and using cruise it seems to kick down more often on the short steep hills rather than the long steep hills. When it kicks down and the clutch fan is engaged the sound scares the hell out of you. I also notice on the kick down the egt's dropped about 150 with the boost in excess of 20#. RPM was around 2900 and no lack of power!!!

The Tow/Haul mode, Cruise control, and transmission shifts are all subsets of the engine management system. According to the Allison web site, the more these are used together, the better they will function together as it continuously accumulates data and make adjustments to the "means" (minimums and maximums) with which lowest emmissions and best fuel conservation possible are sought (to remain within EPA standards).

This means that it "learns" continuously, so the more you tow in T/H mode and the CC, the better it will get at finding the right shift points. That is why many new owners see steady improvements in fuel mileage during the first 30K-50K miles before it levels off. On the other hand, those that start with the pedal to the floor from day one and only tow 1-2 times a year will get quite a difference in performance than those that moderate their driving and tow heavy often.

The programming has certain parameters that are fixed, while others are changed over time. It is good to keep in mind that anything that produces numbers outside of the programming's parameters are tossed out, so when one tries to tow 30K+ uphill both ways at 90 MPH, the monitored numbers will fall outside of those parameters and will be ignored. This takes the system much longer to adjust to the individual's driving style.

I have been asked by others how Radio Flyer's CC can hold when towing heavy in the mountains, while their trucks will kick off soon after starting the same climb. So i've had to do some research, and the above is what I found out. Radio Flyer has been "seasoned" with a light throtle and a lot of weight behind it for over 100K miles. I just enter in different races than most people because I've long known that the one that arrives first, got there long before I set out.

RF

Radio Flyer, when I am towing in the T/H mode and I accelerate lightly, I get a shift from first up to fourth at about 2200 rpm which seems a little high but is ok. From fourth to fifth I have to be going about 65 mph to make the shift. Its turning about 2500 on that one. I have been turning the T/H off just above 50mph when I can achieve lock up and fifth gear. Then I turn it back on to give me grade braking on the way down. Is it best to leave it in T/H all the way. If I only want to go 60mph I will never go into fifth unless I push it to 65+. Is this something that the trans will learn over time. I haven't pulled that much and am normally quite light on the throttle. Thanks

MaxOD,

A very good question, to which I wished I had an answer for you. In your Sig. it shows Juice/***. If these devices generate engine readouts outside the "parameters" of the engine management systems (emissions, economy, engine, trans, and torque inverter temps), then the data is disguarded (so as to not inversely affect the "learning" process? Don't realy know). If I had the time and hardware to do so, I'd hack the code to see what it does, what it looks for, and what it does when it makes adjustments.

Shooting from the hip, I'd say it only delays or extends the learning process, not invalidates it. I had a 2500 ('99, 4X4, H-D Tow, 6.0L, 3.73 & 9,000lbs Fiver) that took a long time to get the shifting down, from what I could tell, since it is so damn gradual.

What I'd experiment with is to get to a speed that gets it to 5th with the cruise, then press the button a few times to lower the CC back down to 60-61 and see if it holds. Doing this several times may give the engine management system some numbers it can live with.

Get back to me with results. Good luck.

RF

Thanks for the reply RF. The converter locks up any where over 50 with the T/H off and by that time I have fifth gear. With T/H on, I have lock up all the way from about 2nd, but it won't shift into fifth until about 65. Once its in it holds with cruise until you hit a hill that comes on quickly. On a hill with the same grade but with a more gradual slope the cruise holds fifth quite well. I was wondering maybe the J/A provides a quicker torque response and causes the trans to shift down too quick. I was running on level 2 and never did think to turn it off to try. I will try that yet as there will be lots of towing this summer. I think the Duramax actually has more than enough power to pull all most any grade without any help from the edge anyway.