Question Anti-Lock Braking Systems (ABS): Answers Reduce a vehicle's normal braking capacity. Are in addition to other braking systems and do not reduce a vehicle's braking power. Are not effective on larger vehicles. Explanation If equipped, ABS is in addition to a vehicle's normal braking system and does not increase or decrease the braking power of any other system. ABS only activates when a vehicle's wheels are about to lock. Take a FREE Practice Test Now This questions appears in the following tests: California Knowledge Test Class A , Michigan Knowledge Test Class A , South Carolina Knowledge Test Class B , Alabama Air Brakes , Alaska Air Brakes , Iowa Air Brakes , Oklahoma Air Brakes , Vermont Air Brakes ,