GM Volt Forum banner

1 - 12 of 12 Posts

Registered
Joined
43 Posts
Discussion Starter #1
When the forward collision avoidance alert lights come on, and make a nice sound 馃攰
Should this also cause the car to stop? Or is "just " and alert?
 

Registered
Joined
6,661 Posts
On a 2017 it should if below 37 MPH. But like most I'm not waiting for the FAB to engage and I'm braking myself.

Guess one way to test this would be to rig up a bed sheet in a deserted mall parking lot and drive at it.
 

Registered
Joined
5,782 Posts
My 2014 ELR so equipped does brake at low speeds. If ACC is engaged, it will stop from any speed as long as it detects the vehicle in the path. If the HUD warning lights up (5 red dots), you better be on the brakes as the car itself doesn't brake hard enough.

ELR makes a sound or vibrates the seat or both depending on how you configure the settings.
 

Registered
Joined
62 Posts
As you experienced when the HUD red collision lights come on, the car does not immediately apply braking. But if the prospect of imminent collision is not rectified within a very short timeframe (I estimate tenths of a second, depending on obstacle closing speed) via your action to brake or otherwise avoid the obstacle, or should the obstacle move itself via speeding up or shifting position, the car will indeed brake for you, and it can potentially be very hard braking.
 

Registered
Joined
2,773 Posts
On a 2017 it should if below 37 MPH. But like most I'm not waiting for the FAB to engage and I'm braking myself.

Guess one way to test this would be to rig up a bed sheet in a deserted mall parking lot and drive at it.
According to the manual, the FAB MUST first detect a vehicle. Maybe if you put a full sized picture of a car on the sheet.

This front automatic braking can only occur if a vehicle is detected. This is shown by the FCA vehicle ahead indicator being lit.

The system works when driving in a forward gear between 8 km/h (5 mph) and 60 km/h (37 mph). It can detect vehicles up to
approximately 60 m (197 ft).

Warning:
FAB is an emergency crash preparation feature and is not designed to avoid crashes. Do not rely on FAB to brake the vehicle. FAB will not brake outside of its operating speed range and only responds to detected vehicles.
 

Registered
Joined
43 Posts
Discussion Starter #7
I have had the RED LEDs and alert when a car in front was making a right had turn, that usually when it Alerts, I'm usually 15-20 ft behind ~+/- 5.. But, never once had the brakes applied.. :( But the adaptive cruise control, will work great, but disengages like 10 mph..
 

Registered
Joined
6,661 Posts
According to the manual, the FAB MUST first detect a vehicle. Maybe if you put a full sized picture of a car on the sheet.

This front automatic braking can only occur if a vehicle is detected. This is shown by the FCA vehicle ahead indicator being lit.

The system works when driving in a forward gear between 8 km/h (5 mph) and 60 km/h (37 mph). It can detect vehicles up to
approximately 60 m (197 ft).

Warning:
FAB is an emergency crash preparation feature and is not designed to avoid crashes. Do not rely on FAB to brake the vehicle. FAB will not brake outside of its operating speed range and only responds to detected vehicles.
Yup, that's what I was talking about. Thanks for the quote from the OM.
 

Registered
Joined
62 Posts
The system works when driving in a forward gear between 8 km/h (5 mph) and 60 km/h (37 mph)
I wondering if this speed specification pertains to cars equipped with DC I/II, but without ACC. DC I/II provide "Low-Speed Forward Automatic Braking", and relies completely on the visual windshield-mounted camera to judge obstacles, distances, and rate of closure. But the addition of ACC comes with a more sophisticated collision avoidance sensor, namely a radar system. Recent IIHS testing demonstrated that there is a significant difference in performance between the two systems, with ACC equipped cars being able to avoid higher speed collisions when DC I/II cars could not. ACC was a late availability addition for 2017, and although described in the OM, perhaps its full collision avoidance capabilities were not added to those specs. I'm fairly certain that I've experienced the HUD warning lights at speeds greater than 37 mph.
 

Registered
Joined
29 Posts
Tonight I was driving with cruise control on at 60 mph when the lights activated and the brake was applied. Since my foot was on neither the gas nor the brake, it was clear that the Collision Avoidance activated the brake. Since I immediately move my foot to the brake, I don't know how much it would have slowed the car. The tricky thing is that I was way behind the car ahead of me in my lane - I would estimate at least 200 feet, so this really startled me. I never could tell if the car ahead had slowed significantly.
 

Registered
Joined
464 Posts
Tonight I was driving with cruise control on at 60 mph when the lights activated and the brake was applied. Since my foot was on neither the gas nor the brake, it was clear that the Collision Avoidance activated the brake. Since I immediately move my foot to the brake, I don't know how much it would have slowed the car. The tricky thing is that I was way behind the car ahead of me in my lane - I would estimate at least 200 feet, so this really startled me. I never could tell if the car ahead had slowed significantly.
Did you see the red lights on the windshield? If not, it might have just been the ACC doing it's thing versus collision avoidance. Either way, the fact that you are unsure of whether the car ahead slowed is an indication that the car's tech might be (*might* as we don't know either way) better than human situational awareness. Also it's possible that because you were using ACC your awareness level is slightly less than normal, which is probably true for many people. Interesting times...
 

Registered
Joined
58 Posts
Tonight I was driving with cruise control on at 60 mph when the lights activated and the brake was applied. Since my foot was on neither the gas nor the brake, it was clear that the Collision Avoidance activated the brake. Since I immediately move my foot to the brake, I don't know how much it would have slowed the car. The tricky thing is that I was way behind the car ahead of me in my lane - I would estimate at least 200 feet, so this really startled me. I never could tell if the car ahead had slowed significantly.
You sure the brake was applied or did the cruise just disengage and so it just felt like the brake was applied?
 
1 - 12 of 12 Posts
Top