A sensing system and method for automatically deactivating an airbag (46) in a vehicle (10). The sensing system includes a seat weight sensor (52) mounted, for example, in a front passenger seat (16), and an ALR sensor (34) for detecting if an automatic locking retractor (32) is active. Signals from these sensors are received by a seat weight sensor module (50). If the automatic locking retractor (32) is active, then a predetermined weight is subtracted from the weight reading detected by the seat weight sensor (52) to produce a weight value prior to comparing the weight value to a predetermined threshold value. If the threshold value is larger, then the sensor module (50) signals the airbag module (48) to deactivate the airbag (46).