GM Service Manual Online
For 1990-2009 cars only

Ignition Key Warning Alarm

The DOME fuse applies battery voltage at all times to the key-in switch in the ignition switch. When the ignition key is inserted into the ignition cylinder, the key-in switch closes, providing battery voltage to the multifunction alarm. When the drivers door is open, the left-front door jamb switch closes and provides a ground signal to the multifunction alarm. When the 2 signals are received, the multifunction alarm activates the ignition key warning alarm, about 2 pulses per second. The alarm continues to sound until one of the following conditions occurs;

    • The ignition key is removed from the ignition cylinder.
    • The drivers door closes.
    • The ignition switch is turned to the ON position.

Headlamp Warning Alarm

The headlamp warning alarm - continuous tone sounds when the following conditions are met:

    • The light switch is in the PARK or the HEAD position.
    • The ignition key is removed from the ignition cylinder.
    • The drivers door is open.

The TAIL fuse applies voltage at all times to the TAIL relay. When the light switch is in the PARK or the HEAD position, ground is supplied to the coil of the TAIL relay. This energizes the coil and closes the contacts, applying battery voltage to the multifunction alarm. With the drivers door open, the left-front door jamb switch provides a ground signal to the multifunction alarm. When the 2 signals are received, the multifunction alarm activates the headlamp warning alarm. The alarm continues to sound until at least one of the above conditions is not met.

Seat Belt Warning Alarm

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.