GM Service Manual Online
For 1990-2009 cars only

The seat belt warning alarm (about 2 pulses per second) activates when the following conditions are met:

    • The ignition switch is in the ON position.
    • The drivers seat belt is unbuckled.

The multifunction alarm applies and monitors voltage across a fixed resistor to the seat belt switch. When the drivers seat belt is unbuckled, a path to ground is provided to the multifunction alarm through the seat belt switch. The alarm sounds for about 6 seconds. If the drivers seat belt is buckled while the alarm sounds, the alarm stops.

The seat belt indicator is provided battery voltage when the ignition switch is in the ON or START positions. If the seat belt is not buckled, the switch will remain closed providing a path to ground for the seat belt indicator. With power and ground provided, the indicator will illuminate. The indicator will remain illuminated until the belt is buckled or the vehicle is turned off.

The switch also provides a path to ground to the inflatable restraint sensing and diagnostic module.