345b throttle issue

hey guys, i got a 345b that idles down by itself. had this problem last year and found the speed sensor wire was rubbed threw and grounding out. fixed it but in the past month its been doing the same thing. just got hooked up with ET and found an active code when the engine hits 1500 rpm, its a 587-2 code, engine governor position sensor. i can't find anything on SIS and i know this engine doesn't have a governor and theres no governor position sensor on the schematic. anyone else ever come across this code?

If your engine is electrically controlled rather than mechanically the ECM likely uses the speed sensor on the flywheel. If it does might want to check the ring gear for ripped up teeth. They can glitch the ECM and mess things up. If you have a scope plug into the signal and see if it's clean.
Later Bob

We need a serial number to be more help.

Is it a 3176 engine?

Does it go right back down to low idle or to around 1300 rpm? Sound like you may have a problem with the AEC system. Does changing the AEC mode switch or pushing the button on the RH joystick make any difference? If so, it's probably a faulty pilot pressure switch.

Also, try putting the backup switch behind the (RH?) armrest into manual mode and see if that makes a difference?

It's an ags1520 with a 3176. Goes to idle about 700 rpm. Changing the AEC doesn't make a difference and it does work in manual mode without a problem. I changed the implement pressure switch. My next step is to connect with ET and watch to see if the implement switch is turning off by its self