I have a 2017 Pacifica and it gains 10-20 mph going down hill in cruise control (depending of course on grade of hill).
And your question is?
I can’t say it is true of all vehicles, but most of the ones I test will use engine or actual braking to slow a car when cruise in engaged. Worth having checked out.
Apples and oranges but my Corolla gains 5 mph or maybe a bit more going downhill with cruise engaged. Your Pacifica may have more “play” or there may be a problem. It should be new enough to be under warranty. I’d take it to a dealer and see what they say. If you hear, “They’re all like that,” ask to drive a new one and see for yourself.
Some cruise control systems will only maintain vehicle speed by throttle only, they won’t apply the brakes or downshift to keep the speed from increasing whilst going downhill. Some will downshift in an effort to keep the speed from increasing, I’ve never driven a vehicle that will apply the brakes on the driver’s behalf as it pertains to cruise control.
If your vehicle has a system that only uses the throttle to control speed, then yeah it could easily gain speed going downhill. Doesn’t necessarily mean there’s anything wrong.
Has your Pacifica had any software updates? Apparently, there is an acceleration problem with some 2017 Pacificas. The van accelerates up to 20 mph faster than the set speed. This occurs at any time, not just when going downhill. You might contact the dealer you work with to see if there are software updates for your van.
I have a date at the dealers.
The engine is used most of the time and the vehicle can still gain speed but not go into free wheeling as this car does.
Sounds like it is not downshifting like it should to maintain speed , thats the way it works on our 14 GC . Think it works the same on my 2020 Durango . It will downshift to hold the speed within a few mph .
I believe that is the problem.
Your operating manual tells you not to use cruise control on hills.