What is the difference between an engine with a mechanical throttle lever and one with an electronic (drive-by-wire) throttle?
With a mechanical throttle the pedal or lever moves the throttle plate or the fuel pump lever directly, via a cable or rod. With an electronic throttle the pedal is only a position sensor; the plate is driven by the engine's ECU. Since the GS740 family moves the mechanical linkage with a cable-pull servo, it is suitable only for the first group.
The difference is set by the physical connection.
- Mechanical throttle: there is an uninterrupted wire/rod between the lever and the plate. The position of the lever determines the fuel quantity directly. Friction and hysteresis can occur in a Bowden cable, which is why the routing matters.
- Electronic throttle: the pedal usually has a dual-channel position sensor and a separate motor drives the plate. The ECU inserts faulty-signal monitoring, idle control and emission strategies in between.
The GS740 and GS740-3P ride on top of the mechanical line: they pull the cable and take the lever to the position you want. For that reason they have no job to do on an engine with an electronic throttle; there a solution working at signal level is needed.
One more important distinction: even though the kit makes the mechanical throttle electronic, it does not replace the engine's governor. The mechanical governor stays on the engine and it is the one that regulates the fuel when the load changes. The kit only says where the lever will stop. The closed loop on the GS740-3P is likewise not on engine speed but on actuator position; the AS5600 magnetic encoder measures the angle of the servo shaft and settles it on the commanded position.
Full article: Electronic speed and throttle control on a diesel engine