Well... depending on how sensitive your hands/feet are, you can actually feel the ABS actuator doing its quick test in some cases. Maybe I'm weird, but I can feel when mine does that test as I drive out of my street. On a side note, I've had multiple occasions when reversing out of my garage, I've accelerated a little then applied the brakes to show down at the top. In that process, I've had the ABS do it's self test with my foot on the brake. It ends up making the weirdest sound/feeling. Kind of like a spring being flicked under tension. same !!!!!