Adaptative cruise control

[Homer1959]

This is new to me, and I’m not sure I like it. On a few occasions, the system kicked in and applied the brakes very roughly for no reason.

 

Anyway, I have a question about how the braking system works with Adaptive Cruise Control on long descents. To maintain speed when engine braking is insufficient, the system uses the brakes. I’m not sure I like this, as I’m worried about losing braking power due to overheating. This is my first vehicle that relies on the brakes when the engine alone can’t maintain speed. Is this the usual behavior of this system?

[GMCustomerService]

Hi Homer! We want to hear more about your brakes slamming, as we want to ensure your Adaptative Cruise Control is operating as designed. If you don't mind, please email us at [email protected] with your VIN, as well as "GM TRUCKS-Homer1959" in the subject line. We look forward to hearing from you. By sending us a message, you consent to the information you provide being monitored and recorded by GM or those acting on GM’s behalf, subject to the GM Privacy Statement: https://www.gm.com/privacy-statement.

[JW2024]

My adaptive cruise control does the same thing sometimes. I can be driving down the highway with the cruise control engage with no one around and the truck will aggressively apply the brakes. When I cancel the cruise control, the truck releases the brakes. It has happened enough times that I disabled the adaptive cruise control. 

[rjgvt]

After reading about adaptive cruise control, I only use regular cruise control.

[XY74]

We have ACC on the wife's 2018 Impala, can't turn it off to regular cruise control and it's far too agressive in it's braking.  Despise it.   The ACC in the '25 truck is better, but still far too agressive in slowing down for things I wouldn't even blink at.  With a trailer behind it's ridiculous.  Good news is it can be turned off to regular cruise.  Only time I ever use ACC is occasionally in heavy traffic just to follow the vehicle in front.  The system still needs a LOT of refinement to be worthwhile IMO.  I'm sure the lawyers have something to do with it...........   

[chwilliams]

Adaptive Cruise Control is dangerous and going to kill people if it hasn't already. I only use it on long flat roads in good weather.

 

Curvy roads? Don't use it.

Roads that quickly undulate? Don't use it.

Precipitation of any kind? Don't use it.

Night time? Don't use it.

Dust storm? Don't use it.

 

#1 and #2 above are super easy to reproduce. Head west out of Hood River on I-84 towards Portland, when you hit the curves at Bonneville Dam hold the **** on. That's assuming it didn't already try to kill you in the preceding ~25 miles.

 

Vehicle: 2024 2500 LTZ with 43k miles on the clock.

[JW2024]

Mine would act up on a straight, flat section of road. Day or night. Dry. Wet. Did not matter. 

[Pryme]

I have it on my daily driver car and turned it off immediately it sucks. Regular cruise for me. My brain still works enough to click up or down when I feel it’s needed or turn it off when I don’t want cruise. 

[Chuck FB]

I've only turned it on when I first had the truck and trying to figure out how to turn the cruise on and what the to types of little insignia's on the dash even meant to get that sorted out. I never have put it on the adaptive cruise long enough to have experienced it sense the vehicle in front of me. After seeing some comments on here about how erratic it can be and that there was a thought that it may be testing the brakes if not the harsher application and wearing out the brakes for nothing .. or getting into an accident, I've just skipped the use of it for now. The idea sounded good on paper ... 

 

However I do get the buzzing seat going on and flashing on the dash if I am in town and someone pulls over in front of me in my lane too close at speed but I believe I have the emergency braking in the info centre turned off as I assume that would slam on the brakes also ?

[UWSkier]

Only time I use it is if I'm towing the RV through a construction zone and want to maintain a big gap between myself and the vehicle in front of me.  Rest of the time it's regular cruise.  The algorithm on the GM HDs sucks for adaptive cruise.  My wife's Mercedes is a million times better.  I like the cruise on that thing.  You barely notice it, and it will keep a close enough distance you rarely get cut off.

[KARNUT]

My limited experience with adaptive cruise was on two lane roads or four lanes without turn lanes was the best. I had mine suddenly brake if someone was slowing in the turn lane. It was unsettling I was concerned that I wouldn’t be as engaged as I usually am driving. 

[Ausslo]

Just FYI even with adaptive cruise off the regular cruise still uses the brakes to maintain speed so on down hill runs, even if it is only going 1-2 mph over set speed, it actively engages brakes reducing fuel milage and significantly increasing brake pad wear. If and when I use cruise I disengage on downhill runs to combat this problem. PITA

[Chuck FB]

1 hour ago, Ausslo said:

Just FYI even with adaptive cruise off the regular cruise still uses the brakes to maintain speed so on down hill runs, even if it is only going 1-2 mph over set speed, it actively engages brakes reducing fuel milage and significantly increasing brake pad wear. If and when I use cruise I disengage on downhill runs to combat this problem. PITA

That's good you pointed that out as I was not sure if the brakes were applying or not as there is no way of knowing other than checking with an infra red gun after a longer down hill run. I had mistakenly thought the hill decent was only a feature that operated in 4 low. I don't really care for how it reacts on a downhill with the cruise engaged as it shifts down aggressively which of course makes sense to use the engine braking but needless if I am not that steep a grade and wish there was a setting to prevent that from happening if I don't want it to. But anyway now that I know the brakes are applying I will be even more diligent in turning off the cruise as the odd time I have forgotten until its shifting down and then typically hit cancel. I haven't been towing yet but then depending on what I am towing I would be putting the trans into the manual mode to restrict how high a gear it would shift into and use that to shift down even more to set myself up for the proper speed for a longer down grade. 

 

I don't suppose GM has a way of getting into the ECM to turn certain features on or off like highway tractors have a whole raft of a list of select-able parameters, as that would solve that if the hill decent could be turned off.  

[Ausslo]

4 minutes ago, Chuck FB said:

That's good you pointed that out as I was not sure if the brakes were applying or not as there is no way of knowing other than checking with an infra red gun after a longer down hill run. I had mistakenly thought the hill decent was only a feature that operated in 4 low. I don't really care for how it reacts on a downhill with the cruise engaged as it shifts down aggressively which of course makes sense to use the engine braking but needless if I am not that steep a grade and wish there was a setting to prevent that from happening if I don't want it to. But anyway now that I know the brakes are applying I will be even more diligent in turning off the cruise as the odd time I have forgotten until its shifting down and then typically hit cancel. I haven't been towing yet but then depending on what I am towing I would be putting the trans into the manual mode to restrict how high a gear it would shift into and use that to shift down even more to set myself up for the proper speed for a longer down grade. 

 

I don't suppose GM has a way of getting into the ECM to turn certain features on or off like highway tractors have a whole raft of a list of select-able parameters, as that would solve that if the hill decent could be turned off.  

At night you can see the brake lights activate.

[Chuck FB]

11 minutes ago, Ausslo said:

At night you can see the brake lights activate.

Oh ( makes sense too ) and I've not been driving at night all summer and to be honest past vehicles I could not see any portion of the brake light from the drivers seat while driving to know if they were working or not, that was always a test with a weighty object on the pedal to self check or by backing up to a building to see the reflection. In fact I will have to go out at night now and see if the Chev brake lights will show up at all in the mirror ... or are you forcing the rear camera to come on at highway speed to do this test ?

 

I saw a comment and not sure if it was on this forum from a while back about how fast the brakes were wearing on a truck and I have to wonder if it had something to do with this very issue, the truck applying the brakes on either the adaptive cruise ( which I thought was the only way they applied on their own in high range ... obviously mistaken ) or now realizing even on normal cruise. I could see though on very hilly roads as well as varying traffic, the brakes would be going on far too often for no good reason.