Does the calibration have to be repeated when the cable stretches or is replaced?
Yes. On the GS740-3P the memory stores the actuator angle relative to the cable position at the moment it was taught; if the cable slips, stretches or is replaced, that mapping is no longer valid. Cut the power and wait about 5 seconds, connect the blue wire to GND first and then power up; about 8 seconds after start-up the memory is erased and the upper limit can be taught again.
The calibration does not store the physical length of the cable, it stores at which actuator angle the throttle reaches its upper limit. If anything changes on the cable side, that relationship becomes invalid.
Cases that require recalibration:
- The cable slipped in the clamp or went slack
- The cable or the sheath was replaced
- The servo or the bracket position was moved
- The engine's idle stop screw was readjusted
Steps: erase the memory with the blue wire procedure above, then release the blue wire. Next turn the potentiometer to its lowest setting, tighten the cable taut while the engine is at idle, run up to maximum speed with the potentiometer and briefly touch the blue wire to negative; the green light blinks, after about 8 seconds the throttle does a release-and-return move and the upper limit is stored. From then on the potentiometer redistributes the span between idle and top speed as 0%-100%.
Full article: Electronic speed and throttle control on a diesel engine