Adaptive Cruise Control Failure - Be Careful !!!

[bZ4X]

I made my first long distance journey with bZ4X. As you can see in the video, activated adaptive cruise control (ACC) but car did not detect front car and if I didn't brake, it would crash! This is a very important safety failure, I dont know what is wrong with sensors. I tested this 3-4 times and everytime same problem happend on that rainy journey.

If I compare; I used Volvo XC90, Rav4, Skoda Karoq before with ACC but never had this failure even in very heavy rainy days. Only some days rav4 deactivated ACC and other safety features such as lane assist due to dirty sensors. 

Please see video, I had to brake car last minute and this deactivated ACC. I will report this to Toyota. 

Edit: I set ACC the longest distance, It should follow the front car with minumum 40 m distance @ this speed. 

 

 

[philip42h]

37 minutes ago, bZ4X said:

As you can see in the video, activated adaptive cruise control (ACC) but car did not detect front car

It's difficult to tell for certain from the video clip, but it would appear that it did detect the car in front and then 'lost' it (and once you'd touched the brakes the system was deactivated anyway). Either way you need to take this back to the dealer to investigate / address.

The system shouldn't be that different from that fitted to the RAV4 and, while I don't bother with LTA, the ACC works exceedingly well - including in rain and heavy spray where the system can 'see' rather better than I can!

[philip42h]

To add ... there is a TSB / recall for the LTA system for the bZ4X (amongst others) - you might want to check whether this applies to your car and whether or not the fix has been applied ...

[bZ4X]

28 minutes ago, philip42h said:

To add ... there is a TSB / recall for the LTA system for the bZ4X (amongst others) - you might want to check whether this applies to your car and whether or not the fix has been applied ...

Yes, my dealer confirmed that they applied fix for that. 

[bZ4X]

1 hour ago, philip42h said:

It's difficult to tell for certain from the video clip, but it would appear that it did detect the car in front and then 'lost' it (and once you'd touched the brakes the system was deactivated anyway). Either way you need to take this back to the dealer to investigate / address.

The system shouldn't be that different from that fitted to the RAV4 and, while I don't bother with LTA, the ACC works exceedingly well - including in rain and heavy spray where the system can 'see' rather better than I can!

Actually, I manually turned ACC off and on at the begining of this video. Car didn't detect front car at all! When I was too close I pressed the brake and ACC disabled itself. I tested this with a bigger size car front me and on the middle lane, but I got same problem and sensor didn't detect the front car. Rav4 has safety sense 2.5 but bZ4X has safety sense 3.0, thus I expect much more better and improved detection. 🙄

[Roy124]

Just a thought, are you quite sure you enabled ACC rather than CC? 

The behaviour suggests CC which will maintain speed right to the point of emergency braking. 

[dab1054]

I used the ACC and LTA on several recent long motorway journeys with my bZ4X in really bad weather just like your conditions. For stop-start and cruising I found ACC gave perfect control -slowing down nicely and then starting up again and maintaining a good distance from the car in front. Quite different to your car, so maybe there is a problem.  On these journeys a lot of road grime had built up on the front sensor panel (found after completed journey) but nevertheless the system still worked fine.  

[philip42h]

1 hour ago, bZ4X said:

Actually, I manually turned ACC off and on at the begining of this video. Car didn't detect front car at all! When I was too close I pressed the brake and ACC disabled itself. 

I can only say what I see ... there's a certain amount of "messing about" and setting up at the beginning of the video, and then:

• at 12 seconds in the car is travelling at 62mph with ACC set at 70mph and the road apparently 'clear' ahead - the car should be accelerating towards the set speed
• at 13 seconds, the car has reached a speed of 64mph with ACC still set at 70mph but showing detection of a car ahead - the car should be considering matching it's speed to that of the car ahead
• at 14 seconds, the car has reached a speed of 65mph with ACC still set at 70mph and still showing detection of a car ahead - the car should be considering matching it's speed to that of the car ahead
• at 15 seconds, the situation is that same as at 14 seconds in
• at 16 seconds, the car is still at 65mph with ACC set at 70mph but the road ahead is shown as clear so that the car is free to accelerate again
• at 17 seconds, the situation is that same as at 16 seconds in, but now / shortly we see the car ahead brake
• at 18 seconds, the car is up to 66mph and you have, rather sensibly, decided to "take back control" ...

The video doesn't always show the car in front or the ACC display but I would have expected the system to detect the car in front pretty much throughout the video - and, clearly, it doesn't ...

[Roy124]

Looking at what Philip has said, with my ACC engaged the car will slow when the car in front slows and will continue to slow after that car has pulled off the lane even though my lane is clear. 

[Cyker]

If mine is set to maximum distance the car will leave such a big gap you could fit a jumbo jet into the space  so if that was yours set to maximum distance it does seem like something's not right...  

Does it work properly in the dry or is this what it always does?

I must admit I'm not as familiar with its behaviour under braking as I find the car brakes too late and too harshly for my tastes when closing on slowing/stopped traffic at highway+ speeds, so I quickly got in the habit of just jabbing the cancel button if I see cars slowing ahead, so I can let the car coast down well in advance (rather than continue at the same speed and then suddenly brake, which is what the ACC tends to do), and then re-engage it when the traffic speeds up and starts to pull away again.

 

[G S]

In very heavy rain, my ACC also "lost" a car and shortly after a message popper up to say the system was in active. I just drove manually until next services. When I stopped later the front was filthy so I think it was the sensors got covered in mucky spray and couldn't cope as once I cleaned them off, it didn't happen again

[Roy124]

On Cyker's point, if you do leave 3 bar spacing on ACC it just seems to be an invitation to the following truck to overtake regardless that all lane 1 traffic is travelling at 59.5 mph 😬

[Roy124]

1 hour ago, G S said:

In very heavy rain, my ACC also "lost" a car and shortly after a message popper up to say the system was in active. I just drove manually until next services. When I stopped later the front was filthy so I think it was the sensors got covered in mucky spray and couldn't cope as once I cleaned them off, it didn't happen again

Can someone confirm that the black plastic plate centre of the front grill is the radar dielectric panel? 

[bZ4X]

20 hours ago, Roy124 said:

Just a thought, are you quite sure you enabled ACC rather than CC? 

The behaviour suggests CC which will maintain speed right to the point of emergency braking. 

Yes, first I thought same. I checked that before the video and adaptive cruise control was on not speed limiter.

[bZ4X]

19 hours ago, philip42h said:

I can only say what I see ... there's a certain amount of "messing about" and setting up at the beginning of the video, and then:

• at 12 seconds in the car is travelling at 62mph with ACC set at 70mph and the road apparently 'clear' ahead - the car should be accelerating towards the set speed
• at 13 seconds, the car has reached a speed of 64mph with ACC still set at 70mph but showing detection of a car ahead - the car should be considering matching it's speed to that of the car ahead
• at 14 seconds, the car has reached a speed of 65mph with ACC still set at 70mph and still showing detection of a car ahead - the car should be considering matching it's speed to that of the car ahead
• at 15 seconds, the situation is that same as at 14 seconds in
• at 16 seconds, the car is still at 65mph with ACC set at 70mph but the road ahead is shown as clear so that the car is free to accelerate again
• at 17 seconds, the situation is that same as at 16 seconds in, but now / shortly we see the car ahead brake
• at 18 seconds, the car is up to 66mph and you have, rather sensibly, decided to "take back control" ...

The video doesn't always show the car in front or the ACC display but I would have expected the system to detect the car in front pretty much throughout the video - and, clearly, it doesn't ...

Yes footage is correct. This is how they programmed the acc. Last 5 miles car slowly accelerate. You can test it. You will see after 65 car will slowly accelerate to 70.

 

I am pretty sure ACC was active 😊 and didn't detect the front car. I was shocked couldn't beleive like you so thats why I recorded video and test it on different lane with a different size car front me. My driver's license is over 20 years old and I actively use ACC for long-distance travel. Maybe this is my cars failure not a common problem. I wanted to inform others just incase, because this is a serous safety bug. 

[Roy124]

1 hour ago, bZ4X said:

Yes, first I thought same. I checked that before the video and adaptive cruise control was on not speed limiter.

No, speed limiter is a different function.  Cruise control has 2 modes, adaptive and fixed.  I don't know the procedure in the BZ4X, in my Corolla you pressed the CC button to activate ACC or press and hold for 3 seconds IIRC, to engage fixed CC. 

In UK, with busy roads, ACC is probably the better mode.  On the continent with less busy roads and easy passing in lane 2 using FCC is better. 

[Roy124]

One other thought, and this may not apply in your case, is the  ACC override function. 

Closing a slower vehicle, if you indicate you want to  pull out this will deactivate ACC and switch to FCC. Once you have moved to lane 2 and stopped indicating the car will revert to ACC. 

[bZ4X]

3 hours ago, Roy124 said:

No, speed limiter is a different function.  Cruise control has 2 modes, adaptive and fixed.  I don't know the procedure in the BZ4X, in my Corolla you pressed the CC button to activate ACC or press and hold for 3 seconds IIRC, to engage fixed CC. 

In UK, with busy roads, ACC is probably the better mode.  On the continent with less busy roads and easy passing in lane 2 using FCC is better. 

We have a button to choose functions on steering wheel on bz4x. ACC was activated and speed limit you can see that I increased to 70 mph in the video while ACC was on. I will return tomorrow and will test again today weather is sunny lets see tomorrow. 

[Roy124]

BZ4X, the same, and the control for ACC and FCC is the same.  It is possible to select FCC when you thought you had just selected ACC. 

Have a look at your manual and check you have not selected FCC by mistake.  FCC is my TLA. 

[G S]

On 1/2/2023 at 9:20 AM, Roy124 said:

Can someone confirm that the black plastic plate centre of the front grill is the radar dielectric panel? 

I wasn't sure so I washed the whole front of the car and that seemed to work (or could be a complete read herring and just stopping the car and restarting solved it)

[bZ4X]

23 hours ago, Roy124 said:

BZ4X, the same, and the control for ACC and FCC is the same.  It is possible to select FCC when you thought you had just selected ACC. 

Have a look at your manual and check you have not selected FCC by mistake.  FCC is my TLA. 

I am %100 ACC was active, you can't confuse them as CC has a different logo. You can make sure ACC was active too just watch video you will only see lane and and horizontal distance lines when ACC active not CC. 

Like below one frum user guide:

[bZ4X]

Hello everyone I tested my bZ4X again on the motorway with 1 hour driving under different conditions. My results:

 

1) If the bz4x sensors adjust the car's own speed relative to the car in front, you will see a car logo like the one below.

 

2) if road is clear or cannot detect car front, then car logo dissappears! Please see below picture:

 

And somehow bz4x sometimes doesn't detect front car or cant decide 😊. Maybe  spray thrown up by vehicles affects the sensors. 

 

I recorded another video today on the return way. And my main concern is not ACC but emergency break. If acoustic sensors cannot detect the distance between two cars won't be able to perform emergency brake as well. See after 00:17 lost the detection! Again, I had to brake to avoid crushing front car at the end of the video. 

 

 

[philip42h]

19 minutes ago, bZ4X said:

You can make sure ACC was active too just watch video you will only see lane and and horizontal distance lines when ACC active

As well as the vehicle in front when the system detects it ... and then loses it again ... 😞

There's something not right and you probably need to get the dealer to look at it.

[bZ4X]

2 minutes ago, philip42h said:

As well as the vehicle in front when the system detects it ... and then loses it again ... 😞

There's something not right and you probably need to get the dealer to look at it.

Thats right it might be only my car. Just wanted share with you as this is a serious safety problem. I will send an email with all my videos and experiences. They should check car logs and report to Toyota JP. 

[philip42h]

3 minutes ago, bZ4X said:

See after 00:17 lost the detection!

Wow! That's really odd. They do say that the system may miss a car cutting in in front of you, but, in this case it just lost sight of everything.