Question What color light indicates a vehicle's ABS is not working? Answers Green Blue Yellow Explanation On vehicles with Anti-Lock Braking Systems (ABS), yellow malfunction lamps alert the driver to ABS malfunction. Take a FREE Practice Test Now This questions appears in the following tests: Florida Knowledge Test Class A , Oklahoma Knowledge Test Class A , South Dakota Knowledge Test Class A , Idaho Air Brakes , Kentucky Air Brakes , Missouri Air Brakes , South Carolina Air Brakes , Vermont Air Brakes , Wyoming Air Brakes ,