Question for GM 6.6 Diesel Owners with 10 speed Allison

[LMagelitz]

I haven’t figured this out yet, so I’ll ask the group. Ford owners, if you experience this, feel free to chime in.

When descending a hill in tow/haul mode, as I get on the brake, the tranny will downshift to help hold back the truck. If I continue on the brake, it will continue to downshift to the point the engine may bump up to 3000+ rpm. This is all without the exhaust brake on. On a lot of gradual short descents, I don’t want it to downshift that much. One gear would be plenty. The only way I’ve figured out how to defeat this is take it out of tow/haul mode.

Anybody have any thoughts?

[Hoopy Frood]

Does it act differently if you have the exhaust brake engaged?

[2Amy4805]

That is exactly what I do is take it out of tow haul mode and push the exhaust brake button. I know why the tow haul is there but I actually drive with out it because it keeps my RPM lower. I have a 23 2500 crew cab LTZ.

[Hoopy Frood]

So you don't engage the exhaust brake while in Tow Haul mode?

[ManageIT]

Ford owner chipping in here...it has been a while since I've been in any significant hills or mountains. I want to say holding the break will only downshift once? I believe I have to lift my foot and brake again to get another down shift. If it is very steep downhill grade, I lock out the top couple gears.

[Redapple63]

I haven’t figured this out yet, so I’ll ask the group. Ford owners, if you experience this, feel free to chime in.

When descending a hill in tow/haul mode, as I get on the brake, the tranny will downshift to help hold back the truck. If I continue on the brake, it will continue to downshift to the point the engine may bump up to 3000+ rpm. This is all without the exhaust brake on. On a lot of gradual short descents, I don’t want it to downshift that much. One gear would be plenty. The only way I’ve figured out how to defeat this is take it out of tow/haul mode.

Anybody have any thoughts?

I don’t have the 10 speed, but my 6 speed Allison does the same thing. I use the exhaust brake which does minimize that. I prepare for a steep descent by getting to my speed before the downhill starts, that makes it much easier to maintain that speed without hitting the brake.

Bill

[Redapple63]

So you don't engage the exhaust brake while in Tow Haul mode?

I know this is not aimed at me, but wanted to share my experience. No, normally I don’t use the exhaust brake unless there are hills that I need to contend with, then absolutely yes, I engage the exhaust brake.

[2Amy4805]

So you don't engage the exhaust brake while in Tow Haul mode?

Okay to be honest,its been a while since I traveled down steep grades but if my memory serves me right the exhaust brake didn't work in the tow haul mode. After I took it out of tow haul that is when I noticed the exhaust brake doing what it is suppose to do.

[Hoopy Frood]

Wow, if your exhaust brake doesn't work in Tow Haul mode, I'd head back to the dealer to get that fixed. The Ram can be set to Auto, Heavy, and Normal, both in Tow Haul and out of Tow Haul.

[huntindog]

Okay to be honest,its been a while since I traveled down steep grades but if my memory serves me right the exhaust brake didn't work in the tow haul mode. After I took it out of tow haul that is when I noticed the exhaust brake doing what it is suppose to do.

On my GM, the EB works in regular mode, and is much more agressive in tow/haul
If CC is engaged the EB will integrete with it to keep the set speed. I have found this works very well... Up to a point. With my previous TT I never had to touch the brake pedal even on the steepest roads. My Momentum at twice the weight will not do it with the CC on the steepest grades. It is much better to manually select the gear you want and then the EB will easily control the speed. Probably shouldn't be in CC on such roads anyway