Another tow/haul question

Thanks for all the input.
I think I'll try it out. I don't like the idea of the high RPM's but it is easy enough to take it out of cruise control. Just tap the brake.
Zulu

billyray50 wrote:
I use cruise control with tow/haul and exhaust brake on full.

Ditto.

I use tow/haul all the time, even when empty. EMpty, it's useful for going down steep hill and controlling my speed when the speed limit is lower. I don't have to use the brakes as much (Allison 6 speed grade braking is what it's called)

Kayteg1 wrote:
Even without tow or engine braking, I found CC on freeway downgrades annoying.
When I pull my cargo trailer I set CC to 65 for fuel saving, but I don't mind to speed up for free on nice long grade on desert even to 80 mph.
Than at 67mph the CC downshift and slows me down.:M

Aye, there's the rub.
With CC set and TowHaul on, it gives the truck permission to hold to whatever speed it was set to.

If it's set to 55 mph going up hill, it will hold at 55 mph.
When it crests the hill and starts downward, it will downshift and hold speed to 55 mph.
It's not a good thing if you prefer to free-wheel on the downhill side.

Tow haul combined with exhaust brake on is recommended by Cummins as the best way to warm an engine in cold weather. It also exercises the vanes on the turbocharger. I usually have mine on all the time. I like the sound of it and it sure helps with these mountains around Houston.

Another, Yes I do use both, never had a problem

Why would you think they would "work against each other?"

Tow/Haul changes shift points and torque converter behavior.

Cruise maintains a steady speed.

To me they seem like they would work TOGETHER, and they do.

I use CC when practical, but when I'm towing, it will force downshifts on grades when it isn't practical, wise, or necessary, so when towing, I only use it on fairly flat stretches. Our truck is a 2004 diesel -- perhaps the newer trucks have more sophisticated CC?, don't know ...

Re exhaust brake, when towing, it's always engaged, irregardless of whether CC is on or off.

Re Tow Haul, when towing, I turn it on and off, depending on driving conditions.

Cruise maintains the speed you set. It will redline the engine if it has to, to maintain the speed you set. It does not know if letting the speed drift down 1MPH, 2MPH, 5MPH, 10MPH is acceptable to you or not. It does not know that it is towing a load.

That's why, as with any "automation" you have to pay attention, use it when it makes sense, and not use it when it doesn't suit the conditions. Automatic transmissions, cruise control, and tow-haul mode all fall into this category.

mkirsch wrote:
Cruise maintains the speed you set. It will redline the engine if it has to, to maintain the speed you set. It does not know if letting the speed drift down 1MPH, 2MPH, 5MPH, 10MPH is acceptable to you or not. It does not know that it is towing a load.

That's why, as with any "automation" you have to pay attention, use it when it makes sense, and not use it when it doesn't suit the conditions. Automatic transmissions, cruise control, and tow-haul mode all fall into this category.

Best answer!!
Thanks!
Zulu

mkirsch wrote:
That's why, as with any "automation" you have to pay attention, use it when it makes sense, and not use it when it doesn't suit the conditions. Automatic transmissions, cruise control, and tow-haul mode all fall into this category.

That's why I miss the manual transmission so much. I was 'one' with the truck. All the perceived advantages of an automatic mostly turned out to be illusory.

My understanding of the tow/haul switch is that it is intended for loads up around the upper one quarter of capacity - - where I never tread. To use it indiscriminately wastes fuel and the 'green meanies' will fly to you in their private jets with their hair on fire and call you a 'climate change denier'.

Our 'new' truck at least has a switch on the transmission column so you can select the gear you want. That's useful in steep grades that will make the cruise control fall off. I can deftly downshift with my thumb to manage the RPMs and hold speed. ...But it's no substitute for a stick and clutch ( shrug ). My head just isn't in the game any more and that's a clumsy way to drive.