Circuit Description

The strut actuator is controlled by the Electronic Suspension Control (ESC) module with a Pulse Width Modulation (PWM) signal. Switching the voltage ON and OFF at a high frequency (2.0 kHz), or pulse width modulating, controls the amount of current delivered to the actuator. By controlling the amount of current to the actuator the Electronic Suspension Control (ESC) module controls the damping force in the strut. A higher level of damping force is achieved by providing correspondingly higher current levels, relating to higher percentages of PWM duty cycle. The default damper state (no battery voltage) is one that provides a minimum damping force.

The ESC module periodically commands each strut actuator to a preset PWM duty cycle in order to override the normal PWM command. During this preset PWM duty cycle, the ESC module is able to perform a diagnostic test on each strut actuator to determine if a malfunction is present. The preset PWM command can be either an OFF or ON state duty cycle.