2020 Cummins IKE pull

4x4ord wrote:

Cummins12V98 wrote:

4x4ord wrote:

ib516 wrote:
I'd be surprised if the service brakes are activated without the pedal being pressed. Yes, I know radar (adaptive) cruise control systems do that and so can those pre-collision things, but that's different than a computer dragging the brakes down a grade. How do they know when to "let off" so they don't overheat? Temp sensors in the brakes now? I can't see that being the case.

I think the exhaust brake slowing the truck activates the brakes lights as they are programmed to do.

I am 100% certain that my Ford operates the truck brakes, trailer brakes, brake lights, exhaust brake and transmission shifting automatically when the auto exhaust brake is selected. It works extremely well.

NOT doubting you but why didn’t the Ford slow the load as well as the RAM?

The Ford applies the brakes to slow the truck to "the set point" which is the speed the truck was going at the time the brake pedal or accelerator was last released. after slowing the truck the brake is released and isn't reapplied until the truck accelerates beyond a certain programmed amount. (I don't remember how much it let the truck accelerate before applying the brakes again). Apparently the amount the computer was comfortable allowing the truck to accelerate was more than what Mr. Truck was comfortable with. The Cummins exhaust brake is either capable of holding an extreme amount of back pressure and so it is holding back without a brake application, as you say, or it is reapplying the brakes at more regular intervals to keep the speed more constant.

I think you've said that if you turn the exhaust brake on and let it hold back without utilizing cruise it doesn't hold back the way it does using cruise ..... I think that is the answer to whether cruise employs the wheel brakes or not ..... evidently it does. The other way you can find out is to go down your 14% grade on cruise with 25000 lbs in tow. When you get to the bottom let the truck coast to a stop, then get out and touch your brake rotors. I'd like to see a video showing the expression on your face the instant your finger touches those cold brakes.:)

When I am towing in the rolling hills around here with my F450 sometimes when I crest the hill the adaptive cruise will take it a couple of mph above the set point on the downhill. If the downhill is steep enough I can feel the exhaust brake kick in followed by the tap of the service brakes if it is steep enough. It is very evident at night with the reflection of the tail lights on the camper. Same thing on long steep downhills it will go 2 or 3 mph above then activate the brakes. This is a 2018 F450 with a combined 28-29k. I think Mr Truck wasn't comfortable going that far above the set point.