Audible Warning Device: Description and Operation

CHIME WARNING SYSTEM
The chime warning system uses a single chime tone generator that is integral to the Central Timer Module (CTM) to provide an audible indication of various vehicle conditions that may require the attention of the vehicle operator. The chime warning system includes the following major components:
- Central Timer Module
- Door Ajar Switch
- Headlamp Switch
- Ignition Switch

The CTM chime warning system circuitry and the integral chime tone generator cannot be adjusted or repaired. If the CTM or the chime tone generator are damaged or faulty, the CTM unit must be replaced.

The chime warning system is designed to provide an audible output as an indication of various conditions that may require the attention or awareness of the vehicle operator. The chime warning system components operate on battery voltage received through a fuse in the Junction Block (JB) on a non-switched fused B(+) circuit so that the system may operate regardless of the ignition switch position.

The CTM has two chime rates: Low: 50 chimes per minute for reminders, and High: 180 chimes per minute for serious conditions that require immediate attention. The high rate chime sounds when the key is left in the ignition and the driver's door is open or if the headlights or the courtesy lights are left on. The low rate chime sounds for any of the other conditions. The seat belt warning chime is activated for 6 seconds, and all other chime conditions will activate the chime once at the same time the warning light on the cluster is illuminated.

The chime warning system provides an audible indication to the vehicle operator under the following conditions:

- Compass/Mini-Trip Computer (CMTC) Reset - The Central Timer Module (CTM) will generate one chime each time a Programmable Communications Interface (PCI) data bus message is received from the optional CMTC indicating that the CMTC data has been reset.

- Door Ajar Warning - The CTM will generate a single chime to announce that a hard wired input from any door ajar switch indicates that a door is open with the ignition switch in the ON position and the vehicle speed is greater than 0 mph.

- Fasten Seat Belt Warning - The CTM will generate repetitive chimes at a slow rate to announce that a hard wired input from the seat belt switch to the Electro-Mechanical Instrument Cluster (EMIC) indicates that the driver side front seat belt is not fastened with the ignition switch in the ON position. Unless the driver side front seat belt is fastened the chimes will continue to sound for a duration of about 7 seconds each time the ignition switch is turned to the ON position, or until the driver side front seat belt is fastened. This chime tone is based upon a PCI data bus chime request message input to the CTM from the EMIC, but is not tied to the operation of the EMIC "Seatbelt" indicator.

- Head/Park/Courtesy Lights ON Warning - The CTM will generate repetitive chimes at a fast rate to announce that hard wired inputs from the driver door ajar switch, headlamp switch, and ignition switch indicate that the exterior or courtesy lamps are turned ON with the driver side front door opened and the ignition switch in the OFF position. The chimes will continue to sound until the exterior or courtesy lamps are turned OFF, the driver side front door is closed, or the ignition switch is turned to the ON position.

- Key-In-Ignition Warning - The CTM will generate repetitive chimes at a fast rate to announce that hard wired inputs from the driver door ajar switch, headlamp switch, and ignition switch indicate that the key is in the ignition lock cylinder with the driver side front door opened and the ignition switch in the OFF position. The chimes will continue to sound until the key is removed from the ignition lock cylinder, the driver side front door is closed, or the ignition switch is turned to the ON position.

- Overspeed Warning - The CTM will generate repetitive chimes at a slow rate to announce that a PCI data bus vehicle speed message from the Powertrain Control Module (PCM) indicates that the vehicle speed is over a programmed speed value. This feature is only enabled on a CTM that has been programmed with a Middle East Gulf Coast Country (GCC) country code.

- Warning Chime Support - The CTM chime tone generator will generate repetitive chimes at a slow rate to announce that a PCI data bus chime request message input has been received from the EMIC or the Airbag Control Module (ACM). These chimes provide an audible alert to the vehicle operator that supplement certain visual indications displayed by the EMIC.

Supplemented indications include the following:
- "ABS" indicator (after prove-out)
- "Airbag" indicator (after prove-out)
- "Check Gauges" indicator
- "Low Fuel" indicator
- "Low Wash" indicator
- "Trans Temp" indicator (automatic transmission only)
- A turn ON reminder warning
- "MIL" lamp (after prove-out)
- CTM entered user program mode
- Button pushed on Compass/Mini-Trip Computer

The CTM provides chime service for all available features in the chime warning system. The CTM relies upon its internal programming and hard wired inputs from the door ajar switches, the headlamp switch, and the key-in ignition switch (ignition switch) to provide chime service for the Head/Park/Courtesy Lights ON reminder, the key-in ignition reminder, and the door ajar warning. The CTM relies upon electronic message inputs received from other modules over the PCI data bus network to provide chime service for all of the remaining chime warning system features. The internal programming of the CTM determines the priority of each chime tone request input that is received, as well as the rate and duration of each chime tone that is to be generated.

The hard wired chime warning system inputs to the CTM, as well as other hard wired circuits for this system may be diagnosed and tested using conventional diagnostic tools and procedures.