Automatic Emergency Braking or Intelligent Brake Assist?

Another JR · April 20

I was on the freeway in fairly heavy rain and the traffic ahead of me suddenly slowed rapidly. I was on it and never came closer than 30 feet from the car ahead of me, but I had the forward collision alert triggered (which I’ve experienced several times before) and, for the first time, at least one of the braking system assist features also triggered. I’m not sure which one, though.

It almost seemed like the truck was already starting to brake as I hit the pedal, but I’m not sure. It definitely was applying more brake than my pedal input. It braked more heavily than I would have in that particular event, but it did its job and kept me from getting near the car in front of me. It sounded sort of like the noise ABS makes, but more of a steady noise rather than the stuttering sound ABS makes.

I was impressed with how well and how smoothly it worked, but I’m curious whether AEB actuated versus just IBA. Anybody able to describe how to tell the difference when the braking is not obviously well before you hit the brake pedal?

BowtieOwner · April 20

13 hours ago, Another JR said:

I was on the freeway in fairly heavy rain and the traffic ahead of me suddenly slowed rapidly. I was on it and never came closer than 30 feet from the car ahead of me, but I had the forward collision alert triggered (which I’ve experienced several times before) and, for the first time, at least one of the braking system assist features also triggered. I’m not sure which one, though.

It almost seemed like the truck was already starting to brake as I hit the pedal, but I’m not sure. It definitely was applying more brake than my pedal input. It braked more heavily than I would have in that particular event, but it did its job and kept me from getting near the car in front of me. It sounded sort of like the noise ABS makes, but more of a steady noise rather than the stuttering sound ABS makes.

I was impressed with how well and how smoothly it worked, but I’m curious whether AEB actuated versus just IBA. Anybody able to describe how to tell the difference when the braking is not obviously well before you hit the brake pedal?

Was this in your '21 HD?

I'm fairly confident that the '20-'23 HDs don't have AEB or IBA, only following distance indicator and forward collision alert. These are just alerts (seat vibration, sound, and lights, if equipped) and don't actually provide braking assistance.

Another JR · April 21

12 hours ago, BowtieOwner said:

Was this in your '21 HD?

I'm fairly confident that the '20-'23 HDs don't have AEB or IBA, only following distance indicator and forward collision alert. These are just alerts (seat vibration, sound, and lights, if equipped) and don't actually provide braking assistance.

Yes it was my 2021 3500hd SLT with convenience and safety packages (forgot what the packages were called). It definitely has those features. They were on the sticker and covered in the manual. The manual says “if you have FCA you also have AEB and IBA.” You can turn them off in the settings, but I have them turned on. One of the two braking features definitely activated, but it’s not clear to me which one.

Edited April 21 by Another JR
Typo

BowtieOwner · April 21

11 hours ago, Another JR said:

Yes it was my 2021 3500hd SLT with convenience and safety packages (forgot what the packages were called). It definitely has those features. They were on the sticker and covered in the manual. The manual says “if you have FCA you also have AEB and IBA.” You can turn them off in the settings, but I have them turned on. One of the two braking features definitely activated, but it’s not clear to me which one.

I stand corrected, just looked up the owner's manual. I don't have the feature on my '22 LTZ, but I did have it on my '21 High Country, and I thought it was only the FCA. I guess I never got into a situation that required the automatic braking, but it is good to know the feature was there. I think I crossed up my thinking because of the Lane Change Alert only being a warning, and is not the same as Lane Keep Assist.

Jettech1 · April 21

I have this package that will alert me as well but I've never felt any brake action at all even when it is alerting me....

SAFETY CONFIDENCE PACKAGE 390.00 • FORWARD COLLISION ALERT • AUTOMATIC EMERGENCY BRAKING • STEERING WHEEL AUDIO CONTROLS • DRIVER INFO CENTER, 4.2"

Edited April 21 by Jettech1

Another JR · April 22

2 hours ago, Jettech1 said:

I have this package that will alert me as well but I've never felt any brake action at all even when it is alerting me....

SAFETY CONFIDENCE PACKAGE 390.00 • FORWARD COLLISION ALERT • AUTOMATIC EMERGENCY BRAKING • STEERING WHEEL AUDIO CONTROLS • DRIVER INFO CENTER, 4.2"

There is a delay between the FCA warning and the application of brakes. I’ve had maybe a dozen FCA warnings, but this was the first one where the brakes did something in addition to what my foot was commanding. I suspect the delay is longer when the the closure rate is lower. In this case it seems like there was maybe a full second delay, but not much more.

Jettech1 · April 22

2 hours ago, Another JR said:

There is a delay between the FCA warning and the application of brakes. I’ve had maybe a dozen FCA warnings, but this was the first one where the brakes did something in addition to what my foot was commanding. I suspect the delay is longer when the the closure rate is lower. In this case it seems like there was maybe a full second delay, but not much more.

My 2019 Ford Explorer Sport used to brake all the time. It was kind of annoying because I was always aware of what was going on. My truck says it has this feature, but I've never felt it. Even when the lights go off and alerting me. Never once when I know what's going on and I'm closing in on someone...not once has it ever hit the brakes for me. The red lights show up and the sounds....but the brakes......nope...

Another JR · April 22

That was my experience too prior to this recent event. I think the difference was I was going fast and the slowdown in front of me was very sudden. The thing did its job very well. I’m just trying to understand whether the AEB fired right before I hit the brake.

Jettech1 · April 22

5 minutes ago, Another JR said:

That was my experience too prior to this recent event. I think the difference was I was going fast and the slowdown in front of me was very sudden. The thing did its job very well. I’m just trying to understand whether the AEB fired right before I hit the brake.

I think it's a nice feature but do I trust it?? Hell no...It has not once starting braking for me when the red lights and sounds are going off. Not once.

NWStever · April 26

I disabled AEB as I don't want to risk inadvertent (false positive) hard braking because the system has confused an oncoming vehicle safely in its own lane as an imminent threat. I left the red warning alert enabled which I note sometime goes off as I approach an inside (RH) curve with an oncoming vehicle presenting the camera a collision threat. Seems like a recipe to get rear-ended.

As for Another JR's experience with enhanced braking, I believe the owner's manual describes an enhanced braking performance capability when the brakes are applied quick and hard by the operator. The reason being to give an initial extra braking capability that improves stopping distances of our big and heavy trucks. Check out the owner's manual for more details of the braking system enhancement.

Another JR · April 27

7 hours ago, NWStever said:

I disabled AEB as I don't want to risk inadvertent (false positive) hard braking because the system has confused an oncoming vehicle safely in its own lane as an imminent threat. I left the red warning alert enabled which I note sometime goes off as I approach an inside (RH) curve with an oncoming vehicle presenting the camera a collision threat. Seems like a recipe to get rear-ended.

As for Another JR's experience with enhanced braking, I believe the owner's manual describes an enhanced braking performance capability when the brakes are applied quick and hard by the operator. The reason being to give an initial extra braking capability that improves stopping distances of our big and heavy trucks. Check out the owner's manual for more details of the braking system enhancement.

I have had two cases like you described where, in a right curve, an oncoming car switched to the center left turn lane, pointing their car at me briefly and setting off the red warning light. In both cases, if the car had actually been coming at me at that speed and distance, a head-on would have been unavoidable, so you’d think any automatic braking would have been applied immediately. However, in both cases, the brakes were not applied by the vehicle. I was reacting and covering the brake in each case, but both times the threat went away before I applied much brake if any. That makes me wonder if it’s not programmed to apply AEB in a head-on detection, maybe due to the false alarm propensity. Just a guess, though. None of the material I’ve found addresses behavior of the system in head-on warnings.

I will say the system has given me numerous legitimate rear end warnings, zero rear end false alarms, and only those two well understood head on “false” alarms, that really were legitimate warnings until the other car changed direction away from pointing at me. The only brake inputs I’ve experienced were in the recent potential rear end event I described in the first post here, and as you said those may have been just IBA and not AEB. No unwanted braking. That’s in two years and 8,000 miles of mixed driving. Nothing about that record makes me distrust the system, so I’m leaving mine turned on.

Edited April 27 by Another JR
Clarification of descriptions