F250 Cruise uses brakes

[Wanna EB]

After hearing different views on the topic, I was finally able to determine that yes in fact a 2017 F250 applies the house and trailer brakes when needed during a decent to maintain speed. Originally, I thought it used only the exhaust brake, but now that I know, I thought I would pass it along.

[turk123]

Originally Posted by Wanna EB

After hearing different views on the topic, I was finally able to determine that yes in fact a 2017 F250 applies the house and trailer brakes when needed during a decent to maintain speed. Originally, I thought it used only the exhaust brake, but now that I know, I thought I would pass it along.

That is very interesting. And here I thought it was the engine brake. Where is this documented? If it is true, it means the brakes could get very hot on a long downhill something I did not anticipate.

[nryn]

I have a 2019 F-250 6.2 with adaptive cruise. In tow/haul mode it uses a combination of brakes and downshifting to slow down (I tested this extensively over the many mountain passes between Illinois and Alaska this summer). It seemed to recognize declination and downshift, but I couldn’t figure out the set of conditions under which it would downshift vs. brake.

I decided I wasn’t comfortable with how often and how long the brakes were being applied on descents. So I basically enabled cruise on flats and uphills then paused it for downhills, as I found manually selecting a gear (still in D but in tow/haul mode you can specify a top gear manually) was the best way to limit speed on a descent. If I time it right I don’t have to use my brakes at all or just tap them to get below a speed threshold for a given gear. It worked very well.

Then towards the bottom of a hill I would resume cruise and increase the top gear.

[turk123]

Here is one article:

https://www.theglobeandmail.com/glob...ticle38316411/


Clearly states NOT to use cruise control. I guess manual gear shifting to go down hill with a diesel F-250?

[mikeinca]

Normal cruise control modulates throttle position to stay at a set speed but if the throttle is fully closed and engine braking isn't enough to slow the vehicle when going downhill, for example, it will keep accelerating. You'd better get on the brakes yourself because cruise won't automatically apply them. Moreover, in every vehicle I'm aware of, applying the brakes will automatically disable cruise control and it must then be reengaged by the driver.

Adaptive cruise works differently and may engage braking if required, if that's what the OP is referring to. I don't think I'd rely on it in a towing situation while descending a grade. I think the OP should clarify the type of cruise control being referred to so people don't get the wrong impression of cruise control's capabilities.

[Wanna EB]

I do in fact have adaptive cruise, but have observed automatic braking when there is no vehicle in front of me. I figured it out by observing the trailer brake gain on the info screen. It would go from zero to 3,4,5, or whatever it needed to to slow the rig to the cruise speed. Again, without anyone in front of me.
I don’t know if this applies to non adaptive cruise but I would guess that it does. Observing the amount of brake gain on a decent when not touching the brake would verify it. When I am trying to keep cool brakes, I only use the exhaust brake and no cruise.

[mikeinca]

Originally Posted by Wanna EB

I do in fact have adaptive cruise, but have observed automatic braking when there is no vehicle in front of me. I figured it out by observing the trailer brake gain on the info screen. It would go from zero to 3,4,5, or whatever it needed to to slow the rig to the cruise speed. Again, without anyone in front of me.
I don’t know if this applies to non adaptive cruise but I would guess that it does. Observing the amount of brake gain on a decent when not touching the brake would verify it. When I am trying to keep cool brakes, I only use the exhaust brake and no cruise.

Thanks for the clarification that you have adaptive cruise.

As far as a non-adaptive cruise control is concerned there is no brake involvement by the system at all; not on the part of the TV or the trailer. The only braking that occurs with non-adaptive cruise, under any circumstances including descent of a hill, is if the driver applies the brakes manually to slow the rig. As soon as he/she touches the brakes non-adaptive cruise control is disabled, just as with adaptive cruise, and must be reengaged manually.

Adaptive cruise is pretty cool...my wife has it on her car....but I wouldn't want to use it towing a trailer down a grade for reasons that have been mentioned.

[uncle_bob]

Hi

On my F-250 (without adaptive cruise) I never see the trailer brakes come on under automatic control. Put another way - the "trailer brake gain" never pops up unless I put my foot on the brake pedal. Indeed the engine downshifts. If that's not enough, the rig simply speeds up (possibly to a crazy speed .....)

Bob

[majorairhead]

My 2017 F250 XLT crew cab 4x4 6.2 gas engine truck DOES NOT use brakes when in cruise control.

In tow/haul mode it WILL downshift to attempt to maintain speed downhill.

[rbs]

Originally Posted by majorairhead

My 2017 F250 XLT crew cab 4x4 6.2 gas engine truck DOES NOT use brakes when in cruise control.

In tow/haul mode it WILL downshift to attempt to maintain speed downhill.

we have 2017 Power Stroke, and it doesn't apply the brakes either

[Wanna EB]

This was a super helpful discussion...thanks for the great info. It is interesting and good to know that the difference between adaptive and regular cruise, particularly given that it is not intuitive that there would be a difference when no vehicles are present. I suppose that the regular cruise does not have a module which activates the brakes and given that the adaptive cruise does, they decided to use it, not only in the case of managing the distance from traffic, but also in the case of a decent without traffic...interesting although I am not sure I like the idea. Without a good sense of what's going on, it would be easy for the driver to assume that the exhaust brake (diesel only of course) is doing the work which may be partially true, but the house and trailer brakes are could be heating up without the driver's knowledge.

[JonDNC]

If you have a diesel and enable automatic engine braking it will leverage that while using either cruise control option. Note: it is not engaged automatically you must push the engine brake button as I understand it. I have done that and works like a champ on steep 10% grade coming out of Asheville.

[nryn]

On my gas engine 250, adaptive cruise will slow down (using brakes) if the current speed is greater than the cruise control set speed. It does not matter if a vehicle is present. It should not slow down if current speed >= set speed.

In other words, if you are going 70 and you resume a set cruise speed of 65, the vehicle will brake to slow down. This behavior is true of both kinds of cruise control.

Similarly, your vehicle will brake if there is a vehicle in front of you and that vehicle is going less than your set speed. This is adaptive cruise control. Normal cruise control would presumably just run over that vehicle .

On gas and in tow/haul mode, downshifting seems to mostly happen when accelerating (to achieve set speed) and on inclines (particularly on uphills). As I mentioned earlier, I couldn’t figure out what set of conditions made the truck brake vs downshift when in (adaptive) cruise and tow/haul on a downhill. It did both, but not predictably to me, and used more brakes than I liked.

Uphill/flats: cruise on. Works well most (90%) of the time with an occasional override by me because sometimes the truck seems more eager to accelerate than conditions warrant (I’m fine going slow).

Downhill: I cancel cruise and use manual top gear selection in tow/haul mode and (minimal) brakes to achieve desired descent speed.

Always in tow/haul when the Airstream is hitched.

I suppose everyone will have their preferred method. After trying a bunch of things I settled on this one about 3,500 miles in to a 10,000 mile journey this summer.

[uncle_bob]

Originally Posted by Wanna EB

This was a super helpful discussion...thanks for the great info. It is interesting and good to know that the difference between adaptive and regular cruise, particularly given that it is not intuitive that there would be a difference when no vehicles are present. I suppose that the regular cruise does not have a module which activates the brakes and given that the adaptive cruise does, they decided to use it, not only in the case of managing the distance from traffic, but also in the case of a decent without traffic...interesting although I am not sure I like the idea. Without a good sense of what's going on, it would be easy for the driver to assume that the exhaust brake (diesel only of course) is doing the work which may be partially true, but the house and trailer brakes are could be heating up without the driver's knowledge.

Hi

This distinction is one reason why I was quite happy when the truck the dealer had available did *not* have adaptive cruise. At that point I didn't realize how fragile the Dexter brakes are. Now that I have replaced a full set in under 2 years of use, I'm *very* aware of that.

Bob

[turk123]

Well, the 2017 F-250 also uses engine brake during adaptive cruise control reducing the amount of brake use during towing. Interesting blurb from Ford:

https://www.digitaltrends.com/cars/2...pound-trailer/

The 2019 will control the speed all the way to zero and then start up again.

[mikeinca]

Originally Posted by nryn

In other words, if you are going 70 and you resume a set cruise speed of 65, the vehicle will brake to slow down. This behavior is true of both kinds of cruise control.

Just to clarify, with non-adaptive cruise control, when resuming cruise at a speed higher than the set speed the system will close the throttle and allow the vehicle to slow down by coasting until the desired speed is reached. It does not apply the brakes. Only adaptive cruise control will do that.

This is why if you are descending a steep grade with non-adaptive cruise engaged, unless engine braking alone is able to slow the vehicle, you will continue to accelerate regardless of set speed until you apply the brakes manually.

[pjshier]

Yesterday, I drove most of the way back to Wasilla from Fairbanks through the Alaska Range using adaptive cruise, with the automatic engine brake engaged, gain set to 6 and the instrument cluster set to display towing status.

It was interesting to see the trailer gain indicator progress up to as much as 6 if I adjusted the cruise speed using my thumb on the minus side of the +/- SET rocker switch - like when unexpectedly encountering a yellow recommended speed sign of 45 on a steep descent/curve section in a 65 stretch of road. After the speed approached the new selected speed, the gain bar shrank back to the left and ultimately zero.

I have noticed that in particularly serpentine stretches - with traffic in front - I find it easier to pause adaptive cruise. In sharper turns where the vehicle in front is tracking to the extreme edge of the roadway, it seems like the radar/camera/software interprets incorrectly and can close the gap between us more than I like.

Otherwise, I am a big fan of the adaptive arrangement. But don't know that I would cross a busy street to get it if it wasn't already installed. "Don't try this at home, your mileage may vary..."

[nryn]

I feel like I should make clear that I really like adaptive cruise control (and for that matter, adaptive steering). It really makes the long-haul flats and most inclines very straightforward.

Like most automated systems, there are conditions in which manual control is preferred and / or safer or better. For me, that proved to be significant downhills or short, steep, rolling hills.

[Silver Goose]

This is also how it works on our 2018 Expy 3.5L TT 10-spd. I was at 1st impressed at how well this maintained the set speed up or downhill until I notice the reflection of my brake lights coming on going downhill. At a minimum, this must annoy the heck out of anyone following me. But is also placing undue wear on the brakes on long descents IMO. In most cases, if I hit the cancel button before the brakes activate, downhill speed increase is minimal and I can select a gear manually while keeping an eye on the tach and intermittently braking if needed.

[StreamDog]

Don't think it's been mentioned here, but adaptive cruise can be disabled. It will then operate like regular cruise.