hitachi 200 ex lc want throttle up

Hey guys ive got a 200 ex LC -2 well at first when I started it up id hear the throttle controller making a awful growling chatter noise an when I hit the 4 differ speed control buttons the throttle wouldn't respond, so I went an played with the throttle control box out by the hyd pumps,an then the growling noise stopped, so I had talked to john deer an they said that the sensor on the back side of the controller may be outta adjustment or a electrical issues between controller an computer. but they said to check the the sensor connector for voltages,, so I did an theres a 3 wire connector an I think one wire had around 4.5 volts an one was a ground an my red wire had nuthin on it. but the guy at deer never told me what I should be reading on the wires nor how to test them an how the 4 economy speed buttons innteraxct with the sensor. ive borrowed a friends book but its for new machines an it has the dial control instead of the buttons. can any one help me out hear an give me a run threw on how this throttle opperations work. can any one tell me how to check the input signal from the 4 buttons to the computer an the out put from the compoutor to the throttle control sensor, an yes the green lite in each of the buttons lites up ever time each ones mashed.

hitachi 200 ex lc want throttle up