Abstract: A vehicle occupant restraint system (20) includes an inflatable air bag (41) and an actuatable inflator (40) for, upon actuation, providing inflation fluid for inflating the air bag. A seat belt (105) extends across the vehicle occupant to restrain the occupant. A tongue (110) is connected with the seat belt (105), and a buckle (57) receives and latches the tongue (110) in the buckle (57). A pretensioner (44) is operatively connected to the belt (105). An indicator (59) indicates to the occupant if the tongue (110) is not received in the buckle (57). A seat belt buckle switch (66) is operatively connected to the buckle (57). The seat belt buckle switch (66) has electrically conductive normally closed contacts (74, 76) which open upon insertion of the tongue (110) into the buckle (57). A resistor network is electrically connected to the normally closed contacts (74, 76).