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We picked up our 2017 Volt a week ago. It's a Premier with ACC. It has what I consider to be a serious safety issue regarding cruise control, but I don't know if it's just our car, others with ACC or all of them. Here's the deal... according to the manual (and with every other car I've owned) if you have cruise control set and you press and hold the +RES button, the car will accelerate. When you let go of the +RES button, the cruise control is supposed to set to the current speed. So, if CC is set to 30 and you hold +RES until the car accelerates to 40, when you release the +RES, the new CC speed should be 40, right? Not in our Volt. The car will continue to accelerate to 50, 60, 70 and even 80 MPH. The DIC shows the new CC speed and in our car it shows 80. It's like when you hold a key down on your computer and several key presses go into the type ahead buffer. When you release that key, a bunch of those characters still show up. I've notified my dealer, but am wondering if anyone else has experienced this.
 

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Sounds like a defect. I have a Gen1 and once you release the +RES it will stop at that speed. I would take it to the dealer if it continues.
 

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my 2012 and 2017 both works like 2VoltFamily's does, have it checked out soon, it could be a serious defect
 

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ACC in my '14 ELR is different from other cruise controls. Multiple presses of res causes multiple 1+ or 5+mph increases depending on how hard the control is pressed. (First detent is 1mph. Second detent is 5mph). I don't know what holding it down will do since I always did discrete presses. That said, once you let go of the control it doesn't continue to increase speed set point.

Here is how I use it:
- even though not recommended, I leave cruise 'on' all the time.
- come up to a following speed.
- check that the lead car is detected (car icon is lit).
- press the set button which sets the current speed as the set speed.
- adjust set speed down or up using set/res respectively in 1 or 5mph increments.
- set the gap as needed for comfort. I'm usually on 'near' or tightest gap.
- ACC will follow the lead car up to set speed or down to 0mph.
- disengage using brake, paddle or control.

I usually set ACC 10mph above what others are driving so that the gap is maintained.
 

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I was just reading the 2017 manual with ACC, and it is not supposed to work this way. You should definitely bring it in to get checked.
 

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One other observation reading the OP again. ACC is not analog. Once set, I can adjust ACC way beyond the current speed. The car won't accelerate to that speed until the road ahead is clear. In other words it is not the same as analog because it is adapting to traffic ahead.
 

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I wouldn't' call this a serious safety issue as you have indicated that it tells you what the speed setpoint is on the DIC display and you can always override the acceleration with a simple tap of the brake pedal or cruise button. Annoying maybe, safety issue, no.

Reading the manual about cruise control operation in the standard version versus the ACC version indicates that your vehicle is operating normally (see pages 195 and 198). With ACC it allows you to set a speed much higher than the present speed versus with standard cruise control the speed setpoint is never more than the actual vehicle speed. That's how ACC is supposed to work so that you can set a speed that might be quite a bit faster than the vehicle currently in front of you, which limits the speed by virtue of keeping the gap.

If you are uncomfortable with this then, it's much better and safer to use the accelerator pedal to increase speed by large amounts rather than pushing and holding the cruise control button.
 

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Like Loboc, I drive a '14 ELR.

This is not a bug, it's a feature; it's the "new" way cruise control will work in today's and tomorrow's cars with fine, digital control.

according to the manual (and with every other car I've owned) if you have cruise control set and you press and hold the +RES button, the car will accelerate. When you let go of the +RES button, the cruise control is supposed to set to the current speed. So, if CC is set to 30 and you hold +RES until the car accelerates to 40, when you release the +RES, the new CC speed should be 40, right? Not in our Volt. The car will continue to accelerate to 50, 60, 70 and even 80 MPH. The DIC shows the new CC speed and in our car it shows 80.
This is why you pay attention to the DIC. It won't accelerate up to 80 because just because it can, it will accelerate up to 80 because that's what you've set it to.

I *have* been in the situation before where I have ACC set for my usual highway speed (67mph), and then drop out of ACC when exiting the highway onto a side road. The ACC will still have a setpoint memory of 67mph, so if I hit "RES+", it will try to get to 67mph unless there's another car in its way, even if the side road has a limit of 35mph. I learned quickly that it's important to pay attention to the setpoint, which is conveniently visible on the DIC, and to use "SET-" rather than "RES+" in some situations.

It's like when you hold a key down on your computer and several key presses go into the type ahead buffer. When you release that key, a bunch of those characters still show up. I've notified my dealer, but am wondering if anyone else has experienced this.
But when you hold a key down on the computer keyboard, there's no way for you to tell how many key presses in memory are going to be typed out. With ACC, you can see what the setpoint is.

Loboc, holding the ACC control button up or down will continue to steadily and consistently raise or lower the setpoint in +1 or +5 increments, depending on which detente you're up against, until you release. I use it all the time.

--Chris
 

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Might be a defect but I'm guessing he's holding the button down and thereby "setting" the speed higher than desired. As Loboc mentioned, on the ELR the speed is set according to how long you hold the button down. I'm thinking it's the same system on the Volt. Easy enough to check. Just look at the DIC.

But when you hold a key down on the computer keyboard, there's no way for you to tell how many key presses in memory are going to be typed out. With ACC, you can see what the setpoint is.
This.
 

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Thanks, you folks are great. It appears that the car is working the way it was designed. I'll just have to adapt. It was a surprise is all.
 

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If you hold it down until the car ACCELERATES to 40, that is different than holding it down until the SET POINT says 40. That is likely the distinction/issue to get used to, since the car may not immediately accelerate to the set point you have programmed, given that it is adaptive based on traffic.
 

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We picked up our 2017 Volt a week ago. It's a Premier with ACC. It has what I consider to be a serious safety issue regarding cruise control, but I don't know if it's just our car, others with ACC or all of them. Here's the deal... according to the manual (and with every other car I've owned) if you have cruise control set and you press and hold the +RES button, the car will accelerate. When you let go of the +RES button, the cruise control is supposed to set to the current speed. So, if CC is set to 30 and you hold +RES until the car accelerates to 40, when you release the +RES, the new CC speed should be 40, right? Not in our Volt. The car will continue to accelerate to 50, 60, 70 and even 80 MPH. The DIC shows the new CC speed and in our car it shows 80. It's like when you hold a key down on your computer and several key presses go into the type ahead buffer. When you release that key, a bunch of those characters still show up. I've notified my dealer, but am wondering if anyone else has experienced this.
Every car I've driven since the mid-90's (Buick, Honda, VM, Infiniti, Acura, Toyota) exhibits this behaviour.
- Tap SET sets the cruise.
- Tap RES resumes to the set speed
- Hold RES increases the set speed and accelerates until the new set speed is reached.
- Hold SET decreases the set speed and coasts till the new set speed is reached.

It's sort-of why there is the + and - symbols beside SET and RES. I be surprised to get into a car with cruise and not have that happen.

(OK - I do have to admit that the current 2012 VW does something a little different - long-hold sets the cruise to the current speed, no matter which button pressed).
 

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I had the same thought as the original post on my 2017 Volt with ACC. I went back to the owner's manual and that's how it's designed to work - it's different than my 2011 Volt and every other GM car I've owned over the last 40 years, BUT ... Holding the "resume+" button will increase your speed in 5 MPH increments. Likewise, holding the "set-" button will decrease it in 5 MPH increments.

I did chat with a couple of folks at GM and verified this is the design. Now that I am used to it and there is no surprise, I am happy with it. Never was there any danger - I was aware of the acceleration and quickly disengaged ACC with the brake (or you can use the paddle or the cancel button on the steering wheel or the cruise on/off button). Now, if I want to increase the speed, I either tap the resume+ quickly for each 1 MPH I wish to increase, or cancel the ACC and accelerate to the new speed and set it. The 5 MPH feature is handy when the speed limit increases, say from 60 to 70. Sometimes I overshoot by 5 or 10 MPH, but I watch the display and I can use "set-" to dial in the desired set speed well before the vehicle gets past my intended speed.

I think ACC saved me a speeding ticket yesterday. I took an unpublished detour where Google maps led me on around the closed M-14 freeway in Ann Arbor, going through a park, with a lot of bicyclists. I set the ACC on 35 MPH, and sure enough, at the bottom of a hill, just past a curve was a police car with radar.

My son pointed out to me that his 2016 Cadillac ATS, with regular cruise control (not ACC) has the same operation, with the 5 MPH increments / decrements - page 256 of the owner's manual (http://www.cadillac.com/owners/auto-owners-manuals.html)
 

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- Hold RES increases the set speed and accelerates until the new set speed is reached.
Yes, ACC does increase the set speed as others. However, it won't attempt to accelerate to that set speed unless there is clear road ahead. (Or an undetected stopped vehicle!) Basically, with no other cars on the road, ACC acts pretty much like any other Cruise Control out there.

Thus the numerous and frankly scary warnings in the manual about ACC operation.

And to reiterate the analog nature of past cruise controls. ACC does not move the 'gas' pedal as it operates.
 
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