TL*THE CONTACT OWNS A 2006 CHEVROLET SILVERADO 2500 HD. THE CONTACT STATED THAT THE SMOKE BEGAN TO FLOW INTO THE CAB OF THE VEHICLE AND THE FAN STOPPED FUNCTIONING. THE CONTACT NOTICED THAT THE WIRING HARNESS TO THE RELAY WAS THE CAUSE OF THE FAILURE. THE VEHICLE WAS TAKEN TO AN AUTHORIZED DEALER WHERE THE WIRING HARNESS AND RELAY WERE REPLACED. THE CONTACT CALLED THE MANUFACTURER WHO OFFERED NO ASSISTANCE. THE CURRENT MILEAGE WAS APPROXIMATELY 55,000. THE FAILURE MILEAGES WERE APPROXIMATELY 54,000.