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Don't do this.

2450 Views 4 Replies 5 Participants Last post by  Dunrollin
I was driving on the highway two days ago. 55mph with active cruise control engaged. The car ahead started to slow to make a right turn and was in the bypass lane, but close enough to the travel lane that my sensors picked it up, and started the truck to decelerate. I could see it was clear to continue so I stepped on the throttle to speed up. I guess that confused things because what followed was a jaw-jarring downshift that slammed the car as though it had been struck. Hopefully nothing got damaged. In the future I will dismiss the cruise control before overriding it.
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My trip down to Charlotte, NC last week was the longest trip I've taken in my 2018 F150 with Adaptive Cruise Control (ACC) My normal driving is City driving where I never engage cruise control and even if I make it to an Interstate, I rarely turn on the Cruise Control. I guess it's been a while since I used ACC and forgot how it actually worked, because I had several occasions where I had a similar experience to yours.

With Cruise Control enabled and set to your cruise speed, your truck will maintain that speed if there's no traffic in your lane. If there is someone in front of you in your lane, it will slow you down and pace the vehicle in front of you, leaving adequate stopping distance. If there is a vehicle behind you and no one in front of you, it will speed up to provide adequate spacing in case you need to brake. If you have a vehicle both in front of you and behind you, it will try to split the space in between. This is how things work when ACC is engaged and you don't touch the gas pedal.

What I forgot (multiple times) and I kept doing is that if you step on the gas, you override ACC and your truck will disregard any of the pacing, but ACC stays engaged until you a.) Step on the brake pedal or b.) Shut off Cruise Control.

The problem I had was I would step of the gas to override ACC in certain situations and then when I would take my foot off the gas, the auto-pacing of ACC would kick back in, so if you were too close to the vehicle in front of you, it would do what you describe where it would downshift very quickly to slow down. I don't know of the brakes were ever applied automatically, but I could see how this could cause an accident if someone is tali-gating you.

I stopped using Cruise Control after this happened a couple times to me to stop the severe downshifting (probably not good on the transmission) and to prevent someone from rear-ending me.
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I’m really not a fan of this Adaptive cruise control. My first experience with it was on a company van. The guy in front of me pulled off onto the exit ramp and slowed down rapidly. The stupid van though the guy on the exit ramp was in front of me and not only slowed down but slammed the brakes on. Life for me got very interesting very quickly with the guy behind me . I mashed the throttle an the stupid van didn’t want to get moving for a few seconds. I really don’t need my truck thinking for me.
I always disengage mine when someone is getting off on an off ramp. Never use it in moderate or heavy traffic.
I use mine often. The only issue I have is when I switch to my 2013 F150, set the cruise and forget it is no adaptive.

I can say I really watch for someone turning off as it has over reacted to this a few times.
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