EQUIPMENT DESCRIPTION: TWO AND FOUR PORT RELAY VALVES MANUFACTURED BETWEEN SEPTEMBER 19, 2000, AND FEBRUARY 10, 2001. THESE VALVES ARE USED TO CONTROL EITHER THE SERVICE BRAKE SYSTEM OR PARK BRAKE SYSTEMS ON TRACTORS, TRUCKS, AND TRAILERS. THE VALVE MAY STICK OPEN WHEN A HIGH- PRESSURE APPLICATION IS RELEASED. THESE VALVES CAN BE IDENTIFIED WITH A DATE CODE ON THE VALVE OF 380K, 390K, 400K, 410K, 420K, 430K, 440K, 450K, 460K, 470K, 480K, 490K, 500K, 510K, 520K, 011K, 021K, 031K, 041K, 051K, OR 061K, AND ARE DARK GREEN IN COLOR. WHEN THE VALVE STICKS OPEN, IT CAN RESULT IN A TOTAL LOSS OF AIR FROM EITHER THE SERVICE OR THE PARK BRAKE SYSTEM.