Theory Of Operation

This diagnostic compares the gear shift actuator 1st-3rd position to minimum and maximum threshold values of allowable mechanical positions. The actuator position is read by a position sensor which provides an output signal with Pulse Width Modulation (PWM) at a fixed frequency and duty cycle proportional to the position of the actuator. The PWM duty cycle electrical range is between 10% and 90%. If the position sensor signal is within this electrical range but it indicates the actuator position is outside of its expected mechanical travel, then the diagnostic will be considered failing.