S2000 Under The Hood S2000 Technical and Mechanical discussions.

ABS brakes randomly comes on

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Old 04-24-2009, 03:21 PM
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Double check all the ABS sensor wiring and reluctor wheels. A dented tooth on a reluctor or a sensor that isn't seated in the hub will send a false wheel speed signal to the ABS unit and cause it to activate the solenoids to that wheel. The ABS unit doesn't always see a problem big enough to cause a DTC, it's just doing it's job.

I'd bet you've got a DTC for a faulty wheel speed sensor as well. You replace a wheel bearing or remove a differential recently?
Old 04-25-2009, 02:03 AM
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If you post your tire sizes we can try to figure out if wheel circumference might 'trick' your ABS into seeing different wheel speeds (i.e. slip/skid) causing it to activate. My guess: this it.
Old 04-25-2009, 02:09 AM
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Originally Posted by mikegarrison,Apr 24 2009, 08:45 AM
If the ABS light is on, something is not working right and you probably don't have ABS functionality at all. You need to get the code pulled and find out why that light is on.
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Old 04-25-2009, 05:26 AM
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Ray I had the opposite. ABS just wouldn't work at all. The abs sensor was too far away on one side so would not sense any slip and would not apply abs. I say either pull the code or check to see how far the abs sensor is away from the wheel.
Old 04-25-2009, 06:59 AM
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Originally Posted by EVAN&MONICA,Apr 24 2009, 02:04 PM
brake pulsation is a typical sign of worn out rotors
Dude, the pulsation from ABS is very different in feel than a warped rotor. The tempo of the rapid fire staccato of the ABS kicking is not speed dependent like a warped rotor.
Old 04-25-2009, 07:06 AM
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I agree with the above in the following order:

Take wheels off and visually inspect the sensors and reluctor rings.

Clean the ABS sensors. Even something like dielectric grease or metal shavings can impede the sensor magnets from accurately picking up the reluctor current.

If there is an obvious damaged sensor, then no need to pull the ABS code. It'll probably just indicate a faulty sensor.

The sensor wires are notoriously fragile. Flexing them a few times (like for brake jobs) can crack the wiring internally and not give you any outward indication which sensor is broken.

I had DSS axles and they were a nightmare for the ABS. The reluctor rings didn't match up with the ABS sensor heads (as others have mentioned). Finally wound up grinding out the hole of the ABS sensor bracket to slide the sensors over a few mm. Interesting that DSS swore that there was no problem with their specs.

We've also run different height wheels front to back and the ABS system is pretty forgiving. You'd really have to have multiple inches different in size to have that be the problem.
Old 04-25-2009, 08:02 AM
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[QUOTE=CKit,Apr 25 2009, 06:59 AM]Dude, the pulsation from ABS is very different in feel than a warped rotor.
Old 04-26-2009, 02:34 AM
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Old 04-27-2009, 04:43 AM
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Originally Posted by CKit,Apr 25 2009, 10:06 AM
I had DSS axles and they were a nightmare for the ABS. The reluctor rings didn't match up with the ABS sensor heads (as others have mentioned). Finally wound up grinding out the hole of the ABS sensor bracket to slide the sensors over a few mm. Interesting that DSS swore that there was no problem with their specs.

We've also run different height wheels front to back and the ABS system is pretty forgiving. You'd really have to have multiple inches different in size to have that be the problem.
Everyone thinks I'm crazy when I complain about my DSS axles Now I feel better.

+1 about wheels and tire sizing- that would most likely NOT trigger the sensors. My guess is misalignment of rings/sensors, or debris. Otherwise, one must be busted.
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