A satellite sensor system for a vehicle includes an application motion sensor for sensing vehicle motion for the purpose of activating a vehicle safety system, a low power consumption motion sensor for monitoring vehicle motion when the vehicle is parked or otherwise not in a driving mode, and an RF communications interface to allow the satellite sensor system to communicate with the vehicle's electronics control unit. The system withholds power from the application sensor until the low power consumption motion sensor indicates that the vehicle is about to enter a driving mode.