Circuit/System Description
The assist step control module (ASC) controls the running board actuators to extend or retract the running boards. Each actuator consists of an electric motor and a potentiometer. The module supplies a low reference and 10-volt reference source voltage to the potentiometer. The ASC control module monitors the voltage drop across the potentiometer on the position signal circuit. When the actuator shaft rotates, the voltage on the position signal circuit changes. The ASC control module supplies the actuator motor with a 12-volt control circuit and a ground control circuit. The ASC module controls the direction of the actuator by changing the polarity of the control circuits.
The assist step control module (ASC) controls the assist step actuators to extend or retract the assist steps. Each actuator consists of an electric motor and a potentiometer. The module supplies a low reference and 10-volt reference source voltage to the potentiometer. The ASC module monitors the voltage drop across the potentiometer on the position signal circuit. When the actuator shaft rotates, the voltage on the position signal circuit changes. The ASC module supplies the actuator motor with a 12-volt control circuit and a ground control circuit. The ASC module controls the direction of the actuator by changing the polarity of the control circuits.
Operation
A power extend operation will occur with the opening of either the front or rear doors on the assist step on that side of the vehicle. A power retract operation will occur with the closing of both doors on the assist step on that side of the vehicle. A door open/close status switch input is received by the assist step controller through the GMLAN serial data line. The park brake switch and vehicle speed inputs are is also received by the assist step controller through the GMLAN serial data line. The assist steps will be disabled when the disable switch is pushed once. The assist steps will be enabled with a second push of the disable switch.
Each assist step has a bi-directional motor and a hall-effect sensor to detect the position of the assist step. The hall-effect sensors are included with the motor assembly. The polarity on each motor is switched to reverse the direction of assist step travel.