2012 Sportsman 400/500 and EFI Tractor Service Manual 9923412, Page 144Get this manual
500 EFI FUEL SYSTEM 500 EFI TRACTOR SPEED CONTROL
System Operation Overview
Sportsman 500 EFI Tractor models are equipped with speed control system from the factoryThis system is designed to meet various international safety standardsThe speed control system consists of: AECU BSpeed Sensor CAir Control Body Assembly DSolenoid Valve The speed control system utilizes the ECU (A), Speed Sensor (B), Air Control Body (C), Solenoid Valve (D), and engine vacuum from the throttle body to operateAt closed throttle, the solenoid valve (D) is remains normally closed and the slide valve (E) in the air control body is closedAs the throttle opens and engine RPM increases, the increase in vacuum opens the slide valve (E), allowing more air to be drawn into the engineThe speed sensor signal (B) is monitored by the ECUWhen the speed sensor signal rises over 40 Kph (25 Mph), the ECU triggers the solenoid valve (D) to open, allowing atmospheric pressure on top of the slide diaphragm (F)This drops the slide valve (E) down to limit the amount of air entering the engineOnce the vehicle speed drops below 37-40 Kph (23-25 Mph), the solenoid valve (D) closes and the operation repeatsShould the vehicle speed reach 67 Kph (42 Mph), the check engine' light will illuminate on the LCD gauge to indicate there is problem with the systemA