Auxiliary Step / Running Board: Description and Operation

PRINCIPLES OF OPERATION

The retractable running boards are controlled by the power liftgate module and retractable running board motor assembly. The retractable running board motors receive a ground signal from the power liftgate module to deploy and an open signal to retract.

When the power liftgate module is in self-test mode, the retractable running board motor sends a 200 ms pulse to the power liftgate module to verify a deploy/retract command was sent by the power liftgate module. When the retractable running board reaches the fully deployed/retracted position, the retractable running board motor assembly will send a 200 ms pulse to the power liftgate module to indicate the operation is complete.

The power liftgate module receives information from the instrument cluster module (ICM) regarding retractable running board system ON or OFF and set for AUTOMATIC/IN or MANUAL/OUT status.

When in AUTOMATIC/IN mode, the retractable running boards will deploy when a door on the same side of the vehicle is opened. When both doors on the same side are closed, the retractable running boards will retract. The power liftgate module receives door ajar status from the body security module through the UART based protocol (UBP) communications network.

When in MANUAL/OUT mode, both retractable running boards will stay deployed until MANUAL/OUT mode is deselected or vehicle speed is greater than 5 mph.

When an obstacle is detected, the retractable running board will reverse direction. If a second obstacle is detected the retractable running board will reverse direction again. If a third obstacle is detected the retractable running board will stop in its current position until the following conditions are met:
- Change in door ajar status.
- Change in manual (OUT) deploy status.
- Vehicle speed greater than 5 mph.