Upper Limit Teach-In
This is teaching the system, once, the highest throttle position the actuator may reach. On the GS740-3P, after the engine has been brought to its maximum speed with the potentiometer, the blue wire is touched to negative; the green light flashes and after about 8 seconds the upper limit is stored. The potentiometer then works according to this new range.
The purpose of the teach-in is to fit the mechanical stroke of the actuator to the engine's real working range. Without teaching, part of the potentiometer travel can fall into a region that does nothing; after teaching, the full travel of the knob is distributed between idle and the taught upper point.
The order matters. First the cable is connected so that it is taut, and the slack is taken up with the engine at idle. Then the engine is run up with the potentiometer to the highest speed desired. At this point the blue wire is touched briefly to GND; the system gives a confirmation signal and after about 8 seconds it completes the recording with a throttle release-and-return movement.
When determining the upper limit, do not exceed the declared rated speed of the engine. This setting is not an overspeed protection; it only limits the position the actuator may reach. The engine's own governor and its overspeed chain, if present, keep working independently of this setting.
The procedure belongs to the GS740-3P; no step-by-step teach-in procedure is declared for the button-equipped GS740.
Context in which this term is used: Electronic speed and throttle control on diesel engines