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I have a Nissan Primera P12, which got ABS.

When I normally brake, wheels don't lock and car comes to a stop as expected with any ABS system.

Although if I'm travelling a bit fast and hit the brake hard (want to stop in a panic) car seems to forget about ABS and lock the wheels then slip. This happens especially when it's raining and the road is wet and a bit slippery (where ABS supposed to be more useful).

There are no warning lights flashing on the dash.

Is this normal behaviour ? Or should I check the ABS ?

Thanks in advance.

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2 Answers 2

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If you can get all 4 to lock at the same time then systems that detect differences between wheels won't activate. The system would have to be smart enough to detect exceptionally fast stopping of the wheels in order to work in that circumstance. My MR2 and Eclipse are definitely not that smart. Both are very capable of locking all 4 at the same time and skidding. However, get one wheel on ice (or unloaded, such as hitting a large bump) and the rest on tarmac and then the system activates (which is rather unfortunate as it seems to extend the stopping distance instead of reducing it).

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I'm not sure about all 4 wheels. But pretty sure it locks both front wheels. It doesn't unlock unless I get my foot out of the brake pedal. I tried this and had a skid going for about 4-5 seconds. Does that mean ABS is not working ? Should it unlock the wheels when it detects locking front 2 wheels ? (My car is front wheel drive.) –  Madushan Oct 3 '12 at 20:53
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Brian, ABS isn't indended to lower the stopping distance - it is intended to help you keep steerage control while stopping, thus giving you the chance to steer around the hazard. –  Nick C Oct 4 '12 at 10:22
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The newer the car the better ABS tends to be, but you can lock up even the best ones if you try hard. On sheet ice it is safer to disable your ABS entirely unless you have a system which is designed for these conditions.

After seeing a bad crash where a long slide into a collision was caused by ABS not allowing any grip, I remove the fuse for ABS each winter when the snow starts to turn to ice.

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Do any modern cars actually let you disable ABS? –  Parker Oct 4 '12 at 14:52
    
Most - some give you an option to disable, but all the ones I have had require you to pop a fuse out :-) –  Rory Alsop Oct 4 '12 at 14:59
    
Previous owner of my Eclipse hated the ABS so much he installed a switch so he could disable it when he drove it, but re-enable it when other people would drive it. :-) –  Brian Knoblauch Oct 4 '12 at 20:17
    
How exactly does ABS "not [allow] any grip"? By keeping the wheels rolling, ABS should facilitate grip, not prevent it... I've heard people make cases for non-ABS brakes over ABS brakes by citing shorter stopping distance on dry pavement (plenty of grip even when sliding) and deep snow/sand (plowing effect helps stopping), but icy/wet conditions are (in my opinion) where ABS is potentially most helpful in maintaining control of the vehicle. I certainly wouldn't advocate disabling ABS for icy conditions. –  mac Oct 10 '12 at 20:44
    
The way ABS is supposed to work is by releasing and reapplying the brakes based on comparing wheel rotation speeds as one wheel locks up. On ice there is often no difference between wheels, so the system fails entirely - keeping all wheels locked on ice for about 40 feet in the example I mentioned above! –  Rory Alsop Oct 10 '12 at 21:56
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