Abstract: A seat belt usage indicator having a seat occupied sensor and a seat belt reel sensor with an externally mounted indicator light. The seat belt usage indicator system has a sensor positioned in each seat and a seat belt reel sensor corresponding to each seat such that the external indicator light can only be deactivated when the seat belt corresponding to an occupied seat is engaged. To ensure reliability, a plurality of surge absorbing devices which protect the circuitry from any voltage spikes that may occur due to static electricity or other disturbances in the vehicle's electrical system, are provided. Also provided are a plurality of resistors which prevent damage to the device by limiting current. In this manner, a reliable and tamper-resistant seat belt usage indicator system is provided.