IV. Background

Toyota has received complaints of inconsistent brake feel during slow and steady application of brakes on rough or slick road surfaces when the anti-lock brake system (ABS) is activated in an effort to maintain tire traction. The system, in normal operation, engages and disengages rapidly (many times per second) as the control system senses and reacts to tire slippage. If the same brake pedal force is applied under these conditions, in the worst case, this may lead to an increase of vehicle stopping distance and thus raise the likelihood of a crash.