1. An assembly module for a motor vehicle, with an optical sensor system that is suitable for a) monitoring a detection region lying outside of the vehicle, so as to determine the proximity of a user, b) in the event the user is detected in a detection region, monitoring an actuation region arranged within the detection region to determine whether the user is located within the actuation region, and c) in the event the user is detected in the actuation region, triggering a signal for executing an action on the motor vehicle, and wherein the optical sensor system is configured to expend less energy for monitoring the detection region than for monitoring the actuation region.