2019 Safety Feature Problem?

Cuppybear

Member
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2016 CX-5 Touring
Hi, I bought a 2019 Mazda 3 AWD Premium hatchback about 2 months ago. I love it! However, there have been 3 instances where the smart brake support/collision avoidance has kicked in unexpectedly. I'm not sure what the exact safety feature/system is called, but it has to do with braking. All 3 times the car has literally stopped hard, almost to a dead stop. One time I was slowing down behind the car in front of me who was making a right turn, and it stopped me from like 45 mph. All I can gather is it thought I was traveling too close? The other 2 times I was going like 30 on a pretty ordinary road, 1 lane in each direction, and the car suddenly put the brakes on. Neither time did I see anything in front of me. I only know that I was kind of rounding a curve both times and there was an oncoming car so maybe my car misjudged and thought the oncoming car was coming at me? But, that's just normal everyday driving. All 3 times the car also flashes the "Brake" light/message in red on the screen. It's scary because to me it's been so unpredictable because I don't see anything it should be trying to avoid. I'm worried that I'm going to cause an accident-that someone will run into the back of me when I stop so suddenly like that.

Anyone experienced this? I took it to the dealer today and they switched one of the settings, but I don't expect that to do anything. If the car thinks something is there, it will react, no matter the timing setting that is selected. He set it to respond later. They also said I could bring it in on Monday so I will do that. The guy said he hadn't heard of that problem before. They also said there is no way to turn the system off.
 
2 months here, 3 hard brakes as well. I have to recon the 3 times I was too close to the front car. I was going to brake of course but this car teaches you to keep a safer distance.
 
Can any of those features be disabled? Can they be disabled individually or is it all or nothing?
 
Hi, I bought a 2019 Mazda 3 AWD Premium hatchback about 2 months ago. I love it! However, there have been 3 instances where the smart brake support/collision avoidance has kicked in unexpectedly. I'm not sure what the exact safety feature/system is called, but it has to do with braking. All 3 times the car has literally stopped hard, almost to a dead stop. One time I was slowing down behind the car in front of me who was making a right turn, and it stopped me from like 45 mph. All I can gather is it thought I was traveling too close? The other 2 times I was going like 30 on a pretty ordinary road, 1 lane in each direction, and the car suddenly put the brakes on. Neither time did I see anything in front of me. I only know that I was kind of rounding a curve both times and there was an oncoming car so maybe my car misjudged and thought the oncoming car was coming at me? But, that's just normal everyday driving. All 3 times the car also flashes the "Brake" light/message in red on the screen. It's scary because to me it's been so unpredictable because I don't see anything it should be trying to avoid. I'm worried that I'm going to cause an accident-that someone will run into the back of me when I stop so suddenly like that.

Anyone experienced this? I took it to the dealer today and they switched one of the settings, but I don't expect that to do anything. If the car thinks something is there, it will react, no matter the timing setting that is selected. He set it to respond later. They also said I could bring it in on Monday so I will do that. The guy said he hadn't heard of that problem before. They also said there is no way to turn the system off.

I don't think they can be disabled, but I'm not entirely sure. I'm pretty sure it can't be disabled by the driver, but maybe through a diagnostic menu by the dealer? Who knows.

I've had a few instances where the car has braked for me in my CX-9. It happens a lot less often after changing the distance setting in the menus, but even still the car will brake for me if I'm following too closely behind a car that turns too slowly (my fault). The feature is called Smart Brake Support or Smart City Brake Support, depending on how fast you're traveling.

The first time it happened for you, you were likely following to closely or the system didn't think you were braking enough as you approached the turning car. The setting that the dealer changed should prevent that from happening again, but if it does, you're likely just following too closely for the system, and will have to adjust your following distance to prevent it from triggering again.

The other two times are kind of an anomaly.. did the two-lane road you were traveling on have any sort of divider or boulevard between the lanes, or was it just a yellow line? The only thing I can think of is that because of the low speed, the curve of the road, and the lack of physical barriers, the system's camera thinks that you're coming up on a vehicle in front of you, and applies the brakes accordingly. Again, the change to the distance setting might solve this issue, as the car won't trigger the system until it detects a vehicle in closer proximity, and by the time the car in the other lane is close enough, it might also be far enough to the side for the system to disregard it. Hopefully that makes some sense, I'm not sure if I'm explaining myself well enough, lol.
 
My guess is that the sensitivity is set too high. My 2014 has the Tech package and has never done what you described.
 
You can set the sensitivity in the infotainment system. I've set it to react as late as possible and have had no issues in the few weeks I've owned the car. I was able to easily engage the emergency braking system during my test drive.

If it still reacts, I'd go see the dealer. Maybe it needs to be recalibrated.
 
How did you engage the emergency braking system during a test drive? Mine has engaged only once as the system decided I wasn't stopping hard enough, but I wouldn't say it was wrong to do so.
 
I pulled up too close and too quickly to the car in front. I had started breaking and would have made it on time but the system didn't like how the gap was being closed quickly.

I've never had that issue with mine, just during the test drive.
 
I have mine disabled. I don't trust it for these stated reasons. Look for it in the i-Active sense settings.
 
Same thing here. The brakes engaged in 3 instances and I almost had an accident once because of it. I got really scared when it happened.
At one time I merged into slower traffic on the lane to my right and the car slammed on brakes once my speed was adjusted (slowed) to theirs.
The brake action happened with a delay and the guy behind me ended up almost hitting my back. He had to brake so hard that he got smoke from his front tires.

Another instance - I changed a lane and I was doing 60 mph and accelerating and there were no cars in front of me - and this thing engaged hard and I thought I hit something.
I almost hit my head on the steering. That was terrible. But most importantly - I was just in shock because of it. Why would this thing brake like this? Is this car crazy or what?
This one got me more scared than the previous instance. I had to stop and get out and walk a little. I just had to breathe.

I tried disabling this - and on my car it is greyed out. I am not sure how to do it.
But I am planning a dealer visit to have them check on something else and I will make sure they disable it for me.
This thing is dangerous. It is outright scary.
 
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Correct. I thought I had disabled mine, but after checking it I had not. Asked the dealer about it and they didn't think they could turn it off.
 
I just spoke with one of Mazda employees and he told me there are many complaints about this brake system. It seems like it happens to many people - not just us.
This is a terribly screwed up design. It should never be set to ON by default and the fact that it's on at all times is scary.
The dealer outright refused to disable it.

So I think I am going to complain about it to USDT. I think there is no choice.
I like my car and I don't want to return it - but driving like this is unsafe.
So I want to force it upon Mazda to disable it. They have to do it.
I think that communicating it to dealership is just a waste of time.
It is NHTSA time. Done talking with dealer.
 
I just spoke with one of Mazda employees and he told me there are many complaints about this brake system. It seems like it happens to many people - not just us.
This is a terribly screwed up design. It should never be set to ON by default and the fact that it's on at all times is scary.
The dealer outright refused to disable it.

So I think I am going to complain about it to USDT. I think there is no choice.
I like my car and I don't want to return it - but driving like this is unsafe.
So I want to force it upon Mazda to disable it. They have to do it.
I think that communicating it to dealership is just a waste of time.
It is NHTSA time. Done talking with dealer.

Your next line of communication should be to Mazda of North America, not the NHTSA. Should go Dealer > MNAO > NHTSA.

It's possible that escalating to MNAO may result in them stepping in and forcing the dealer to recalibrate the system or replace the components of the smart brake support system in your car. That could potentially resolve the issue. They might even allow the dealer to disable the system if you're willing to sign a waiver. Not sure if any of this is actually possible, but I'm just trying to think out of the box here.

On another note, you could also request that the dealership hold your car while you drive a loaner Mazda3 for a few days to see if the experience is the same. It could be a problem isolated to your car. I say this because if it was such a widespread issue, we would have heard a lot more about it by now.
 
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I found a way to turn off smart city brake support. Turn off i-ACTIVESENSE and you can then uncheck SCBS. At a cost though. Take a look at 4-85 in your owners manual and it will show all
the "services" that i-ACTIVESENSE supports.
 
I found a way to turn off smart city brake support. Turn off i-ACTIVESENSE and you can then uncheck SCBS. At a cost though. Take a look at 4-85 in your owners manual and it will show all
the "services" that i-ACTIVESENSE supports.

Yes. But you got to do it every time. The manual lists on 4-86 Systems which are restored to operational status automatically and it has "Smart Brake Support (SBS)" listed among other settings.
This means that SBS can't be turned off permanently, because once you re-enable the i-ACTIVESENSE - SBS comes right back and then you have to turn it off again.
In addition, when ignition is cycled - the SBS turns on again even if the i-ACTIVESENSE remains OFF.

Finally - i-ACTIVESENSE controls the Blind Spot Monitoring (BSM)
I want this one active at all times so I don't want to disable it.
 
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