Originally Posted by K2e2vin
I concur with PuyallupCoug said. ABS works by calculating the difference between wheel speeds. If there's no difference, it will not engage. This happened to my friends this past two weeks(AS tires in WV snowy mountain roads in late-model Mazda and Toyota).
Fundamental braking technique is if all wheels are locked up, is to let off the brakes and get back on it smoothly.
I don't think ABS compares the difference between different wheels speeds, though VDC does work out how all 4 wheels are moving or not to maintain stability and works with the symmetrical AWD and ABS to regulate the wheel spin.
ABS uses individual sensors on each wheel to regulate the brake pressure for that wheel. But in our cars you cannot separate ABS and VDC.
In general if you are out driving in snow or ice don't try to modulate the brakes yourself, use the push and hold technique and let the car work it out. If there is no traction because your tires (OEM or otherwise) cannot grip black ice, messing with the brake pedal isn't going to help you anyway, and your technique of letting off and getting back on the brakes would not be faster than the car can perform itself.
The only condition where non-ABS stopping is superior is dry summer pavement. In those conditions the car will stop quicker if the wheels lock and skid (flat spot be damned).
Otherwise trust the car to do its thing and blame the lack of traction and lack of braking power on ice, which you can somewhat correct by running winter rubber instead of yoko's.