A stepper motor is controlled by the onboard computer. The computer moves the pintle in and out of an opening that bypasses the throttle blade. This allows the computer to precisely control idle speed when varying loads are placed on the engine. Symptoms of failure include engine stalling, surging, poor idle conditions, and or a check engine light. Check for proper operation with each tune-up. Replace when trouble codes indicate failure. Walker Products began supplying the fuel system needs of the automotive industry since 1946. Today Walker is one of the largest, privately owned manufacturers of fuel system components and engine sensors, and has served the needs of the worldwide automotive aftermarket. As an ISO9001 certified company, We are committed to supplying products manufactured to meet or exceed OEM standards and specifications. Vehicle Fitment: Cadillac Escalade 2002, Escalade EXT 2002, Chevrolet Avalanche 1500 2002, Camaro 2002-2000, Silverado 1500 2002-1999, Silverado 1500 HD 2002-2001, Silverado 2500 2002-1999, Silverado 2500 HD 2002-2001, Silverado 3500 2002-2001, Suburban 1500 2002-2000, Suburban 2500 2002-2000, Tahoe 2002-2000, GMC Sierra 1500 2002-1999, Sierra 1500 HD 2002-2001, Sierra 2500 2002-1999, Sierra 2500 HD 2002-2001, Sierra 3500 2002-2001, Yukon 2002-2000, Yukon XL 1500 2002-2000, Yukon XL 2500 2002-2000, Pontiac Firebird 2002-2000, GTO 2004