Audible Warning Device: Description and Operation

WARNING CHIME -- HOW THE CIRCUIT WORKS

The Central Processing Unit (CPU) is capable of emitting a tone and turning on the Instrument Cluster Fasten Seat Belt Indicator to alert the driver to certain conditions. These conditions include Park Lamps or Headlamps on, key in ignition, key in shift lock and driver's seat belt unfastened.

Voltage is present at the CPU at all times through the ROOM Fuse.

Lamps On Warning

With the Main Light Switch in "PARK" or "HEAD", the Park Lamp Relay is energized and voltage is present at pin P of the CPU. If the Ignition Switch is in "LOCK", voltage is not present at pin A of the Central Processing Unit. Under these conditions, the Module sounds to warn the driver that the lamps are on.

Key In Ignition/Key In Shift Lock Warning

When the Ignition Switch is moved from "RUN" to "LOCK", voltage is removed from pin A of the CPU. If the key is in the Ignition Switch or Shift lock Switch, the relative (Ignition or Shift lock) Ignition Key Reminder Switch is closed and voltage is present at pin I of the CPU. Under these conditions, the module sounds to warn the driver that the key is still in the ignition or shift lock.

Fasten Belts Warning

With the Ignition Switch in "START" or "RUN", voltage is present at pin A of the CPU. Unbuckling the driver's seat belt causes the Driver's Seat Belt Buckle Switch to close, grounding pin K of the CPU. Under these conditions, the CPU sounds. The module also grounds pin B to activate the Fasten Belts Indicator.