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Old 28th November 2014, 18:35   #526
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Default re: The ABS discussion thread

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Originally Posted by Rintu View Post
Sorry, to have caused confusion. ...
a) Had to replace a front wheel speed sensor after the ABS light was flickering. ...
Annunciation standards: Flashing = 2Hz, Flickering = 10Hz. Automotive systems use Flashing, never Flickering. One can't use the words interchangeably, no potaato potayto here.

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Originally Posted by Rintu View Post
... b) The ABS system on my Nissan Maxima will NOT be activated below speeds of 6MPH (which would be around 10kmph). ...
Check the manual again, please!

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... c) I don't think any passenger vehicle come factory equipped with an ABS kill switch. ...
A few do - ABS is not desirable in off-roading.

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Originally Posted by Rintu View Post
... We have compared the stopping distances on Maximas with and without ABS ... Results were mixed with respect to stopping distances. I'll put it this way - In snow, it takes longer (than you think) to come to a stop. ...
Everyone (who contest braking effectiveness of ABS) says that - that they have tested it with and without ABS. The difference is empirical testing v/s testing keeping conditions constant.

I am neither ridiculing your testing nor pooh-poohing your data, but please realize this is not a matter of just going somewhere and pressing brakes to come to such conclusions. Otherwise, with our passion for all things automotive, most of us would have become car systems designers by now by doing empirical testing.

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... I would say, test your car to understand its capabilities and limitations. ...
Oh, that I most certainly have - on road and in controlled testing conditions.
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Old 28th November 2014, 19:23   #527
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Default re: The ABS discussion thread

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A few do - ABS is not desirable in off-roading.
So true. I have experienced this when I hit a long stretch or rough roads with potholes (created by road works) unexpectedly while on a highway drive. The ABS wasn't as effective as it is on a smooth road.
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Old 29th November 2014, 11:16   #528
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So true. I have experienced this when I hit a long stretch or rough roads with potholes (created by road works) unexpectedly while on a highway drive. The ABS wasn't as effective as it is on a smooth road.
So you mean your brakes locked/car skidded when on WIP road?
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Old 29th November 2014, 12:14   #529
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Default re: The ABS discussion thread

In a non ABS vehicle, when the wheel locks up in loose sand, we manually release the pedal and reapply again and this is exactly what ABS does in pretty quick time irrespective of the foot applied pressure.

The video in the following link explains the ABS function properly.

And this link too of XUV5OO with and without ABS.

Last edited by rajeev k : 29th November 2014 at 12:24.
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Old 30th November 2014, 19:53   #530
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Default re: The ABS discussion thread

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Originally Posted by DerAlte View Post
... Automotive systems use Flashing, never Flickering. ...
Must add here: In some ABS systems, dashboard annunciation lamp also shows fault code - a sequence of flashes (one has to count) followed by a longish pause. This repeats.

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Originally Posted by D C View Post
So true. I have experienced this when I hit a long stretch or rough roads with potholes (created by road works) unexpectedly while on a highway drive. The ABS wasn't as effective as it is on a smooth road.
Rapid changes in wheel speed, especially wheel locking and then unlocking in a very short time, confuses the ABS algorithms. In pot-holed road conditions, as in off-roading, it is a nuisance as wheels lock as soon as they lift off the surface, and roll again when making contact.
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Old 20th December 2014, 23:00   #531
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Default re: The ABS discussion thread

Just today the ABS got me in trouble.
My speed was <10kph and the car in front of me stopped so I had to brake hard.
Unexpectedly, the car didn't stop and the ABS kicked in and I rear ended the other car. Since the speed was so low 3-4 kph, there was no damage at all to both vehicles.
I had enough distance from the car, but ABS screwed up everything due to the low traction. The pedal was pulsating till the car hit the other car. Full pressure was applied to the brake pedal.
The reason for this, was the sand on the road due to the overpass construction.The tires had no traction and so the ABS kicked in to keep them from locking up. Funny thing is that locked wheels stop quicker in certain conditions.

I tried to recreate this and braked hard at 10kph with the left tire on dirt and the right tire on smooth tarmac, exact same thing happened.
The ESP did not kick in. I have the Brake assist and EDL to max(strong/early) and running on the stock tires.
I have stopped the car from 120-0 on smooth tarmac with little drama, this tells me that the calibration for the ABS sensor is just stupid, I remember a certain post from an SX4 owner who complained about the ABS when going through potholes.

Has anyone else gone through this? It is not like the car is at super high speeds, it is less that 10! This happened in crawling traffic. This was a scary experience, the pedal was pulsating like crazy and bang! the car rear ends another car. I am so thankful that my speed was so low(<10 km/h), who knows what might have happened if the speed was higher like 20-40.
Car: POLO GT TSI KM:567
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Old 28th January 2015, 16:44   #532
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Default re: The ABS discussion thread

Hi bhpians, I own a Hyundai Elite i20 Asta CRDi and yesterday on a highway I had to brake hard to avoid an accident although nothing happened but the brake pedal had a weird noise of kut kut kut. Is it normal in cars with ABS & EBD? I have a Skoda Laura L&K too but I have never faced this kind of brake pedal juddering. It is really smooth in the Skoda.
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Old 28th January 2015, 17:10   #533
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Originally Posted by ricky_1605 View Post
... brake pedal had a weird noise of kut kut kut. Is it normal in cars with ABS & EBD?...
My Jazz gives the same kat-kat sound and shudders from the brake pedal when ABS kicks in.
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Old 28th January 2015, 17:46   #534
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Default re: The ABS discussion thread

Yes, juddering is exactly what ABS does: applying the brake on/off very fast.

Does the extent to which this can be felt at the pedal vary? Do people regard it as important feedback?
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Old 28th January 2015, 18:41   #535
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Originally Posted by Thad E Ginathom View Post
Yes, juddering is exactly what ABS does: applying the brake on/off very fast.

Does the extent to which this can be felt at the pedal vary? Do people regard it as important feedback?

All it does it tells the ABS is engaged. Not much more to it I would think. So if you are braking hard and you dont feel it there are three possible reasons. Your car isnt equipped with ABS (duh,), the ABS is broken or you are not pushing the pedal hard enough. The last one is more common that you would think. On some cars you might have to push real hard and for instance my wife had trouble doing that. To some extend can be worse if you got yourself in a bad driving position, to close to the wheel and pedals.

Jeroen
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Old 1st June 2015, 23:17   #536
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Default re: The ABS discussion thread

I own 2009 model innova v.The ABS warning light keeps lighting up momentarily .Is it saf e to drive the car or it needs immediate workshop attention .Please enlighten me on this front soon
regards
praveen singh
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Old 2nd June 2015, 00:00   #537
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Default re: The ABS discussion thread

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Originally Posted by H_Dogg72 View Post
Since the speed was so low 3-4 kph
Quote:
I had enough distance from the car
The two comments above seem slightly contradictory. How much distance do you mean by 'enough'? A car length? Less? More? If you had 'enough' space, I can't fathom why you had to slam the brakes given your low single-digit speeds. What am I missing?

Quote:
The reason for this, was the sand on the road due to the overpass construction.The tires had no traction and so the ABS kicked in to keep them from locking up. Funny thing is that locked wheels stop quicker in certain conditions.
Expected ABS behavior on sandy (and other low-traction) surfaces and need to be accounted for while driving. The system has its limitations (and that's why it's not recommended for certain scenarios like off-roading), but you're just assuming you would've 'skidded' to a stop in time had the ABS not kicked in. Not necessarily true.


Quote:
I am so thankful that my speed was so low(<10 km/h), who knows what might have happened if the speed was higher like 20-40.
If you slam the brakes from 40 km/h on such a surface, you ain't stopping within 'several' car lengths, ABS or not.

Last edited by Chetan_Rao : 2nd June 2015 at 00:12.
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Old 2nd June 2015, 00:08   #538
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Default The ABS discussion thread!!

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Originally Posted by blueblooded View Post
I own 2009 model innova v.The ABS warning light keeps lighting up momentarily .Is it saf e to drive the car or it needs immediate workshop attention .Please enlighten me on this front soon
regards
praveen singh

Since the malfunction light is coming up momentarily, please inspect wheel speed sensors for presence of unwanted particles.

Kindly check all connectors related to ABS for loosening that might be causing intermittent glow of malfunction light.

You may try for disconnecting the battery for a min to reset the code (like rebooting an electronic device).
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Old 2nd June 2015, 07:01   #539
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Default re: The ABS discussion thread

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Originally Posted by blueblooded View Post
I own 2009 model innova v.The ABS warning light keeps lighting up momentarily .Is it saf e to drive the car or it needs immediate workshop attention .Please enlighten me on this front soon
regards
praveen singh
You should get it hooked up to a car manufacturers specific OBD analyser. Only way to really figure out what goes on.

Jeroen
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Old 2nd June 2015, 09:08   #540
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Default re: The ABS discussion thread

Quote:
Originally Posted by blueblooded View Post
I own 2009 model innova v.The ABS warning light keeps lighting up momentarily .Is it saf e to drive the car or it needs immediate workshop attention .Please enlighten me on this front soon
regards
praveen singh
As long as you don't have a brake malfunctioning light on, you shouldn't have a problem with braking. Only thing is your ABS might not be working. It's safe to drive. However, do check it up as soon as possible.
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