[Tf175]

Our '86 has an electric over air solenoid mounted on the governor housing . The solenoid has a plunger that pushes against a lever when activated (switch turned off ) . Have not had problem shutting down , but once wouldn't start because the plunger was stuck in shut down position. WD 40 solved issue . Governor is located on passenger side , kind of below pipe from exhaust manifold to turbo. Follow the throttle cable from the Bendix air cylinder , it ends up connected to the throttle lever on the governor . Next door neighbor to the shut down . 
Chris